JetpackのNavigationのオプション、NavOptionsをざっくり覗いてみる ref: https://qiita.com/k_keisuke/items/29cf9f4df7b3cdcbb147

Activit

        /**       
         * 略                                                                                                                                                                   
         * @param launchDocument true to launch a new document task                                 
         * @deprecated As per the {@link android.content.Intent#FLAG_ACTIVITY_NEW_DOCUMENT}         
         * documentation, it is recommended to use {@link android.R.attr#documentLaunchMode} on an  
         * Activity you wish to launch as a new document.                                           
         */                                                                                         
        @Deprecated                                                                                 
        @NonNull                                                                                    
        public Builder setLaunchDocument(boolean launchDocument) {/* 略 */}                               

ActivityNavigator.java

    @SuppressWarnings("deprecation")
    @Override
    public void navigate(@NonNull Destination destination, @Nullable Bundle args,
            @Nullable NavOptions navOptions) {
/* 略 */
        NavOptions.addPopAnimationsToIntent(intent, navOptions);
/* 略 */
}

AfterActivity

  view?.findViewById<Button>(R.id.button_to_activity)?.setOnClickListener {
            val options = NavOptions.Builder()
                    .setPopEnterAnim(R.anim.abc_fade_in)
                    .setPopExitAnim(R.anim.abc_fade_out)
                    .build()
  Navigation.findNavController(it).navigate(R.id.action_mainFragment_to_main2Activity, null, options)
        }

AfterActivity（非推奨な方法)

  view?.findViewById<Button>(R.id.button_to_activity)?.setOnClickListener {
  val options = NavOptions.Builder().setClearTask(true).build()
  Navigation.findNavController(it).navigate(R.id.action_mainFragment_to_main2Activity, null, options)
        }

AndroidManifest.xml

        <activity android:name=".Main2Activity"
            android:documentLaunchMode="always">
        </activity>

BeforeActivity

  val intent = Intent(context, SomeActivity::class.java)
  intent.flags = Intent.LAUNCH_CLEAR_TASK
  context.startActivity(intent)

NavController.java

    public void navigate(@IdRes int resId, @Nullable Bundle args, @Nullable NavOptions navOptions) {
/* 略 */
        if (destId == 0 && navOptions != null && navOptions.getPopUpTo() != 0) {
            popBackStack(navOptions.getPopUpTo(), navOptions.isPopUpToInclusive());
            return;
        }
/* 略 */
    }

    /**
     * Attempts to pop the controller's back stack back to a specific destination.
     *
     * @param destinationId The topmost destination to retain
     * @param inclusive Whether the given destination should also be popped.
     *
     * @return true if the stack was popped at least once, false otherwise
     */
    public boolean popBackStack(@IdRes int destinationId, boolean inclusive) {
        if (mBackStack.isEmpty()) {
            throw new IllegalArgumentException("NavController back stack is empty");
        }
        ArrayList<NavDestination> destinationsToRemove = new ArrayList<>();
        Iterator<NavDestination> iterator = mBackStack.descendingIterator();
        while (iterator.hasNext()) {
            NavDestination destination = iterator.next();
            if (inclusive || destination.getId() != destinationId) {
                destinationsToRemove.add(destination);
            }
            if (destination.getId() == destinationId) {
                break;
            }
        }
        boolean popped = false;
        iterator = destinationsToRemove.iterator();
        while (iterator.hasNext()) {
            NavDestination destination = iterator.next();
            // Skip destinations already removed by a previous popBackStack operation
            while (!mBackStack.isEmpty() && mBackStack.peekLast().getId() != destination.getId()) {
                if (iterator.hasNext()) {
                    destination = iterator.next();
                } else {
                    destination = null;
                    break;
                }
            }
            if (destination != null) {
                popped = destination.getNavigator().popBackStack() || popped;
            }
        }
        return popped;
    }

NavOptions.java

    /**                                                                                              
     * Add the {@link #getPopEnterAnim() pop enter} and {@link #getPopExitAnim() pop exit}           
     * animation to an Intent for later usage with                                                   
     * {@link #applyPopAnimationsToPendingTransition(Activity)}.                                     
     * <p>                                                                                           
     * This is automatically called for you by {@link ActivityNavigator}.                            
     * </p>                                                                                          
     *                                                                                               
     * @param intent Intent being started with the given NavOptions                                  
     * @param navOptions NavOptions containing the pop animations.                                   
     * @see #applyPopAnimationsToPendingTransition(Activity)                                         
     * @see #getPopEnterAnim()                                                                       
     * @see #getPopExitAnim()                                                                        
     */                                                                                              
    public static void addPopAnimationsToIntent(@NonNull Intent intent,                              
            @Nullable NavOptions navOptions) {                                                       
        if (navOptions != null) {                                                                    
            intent.putExtra(KEY_NAV_OPTIONS, navOptions.toBundle());                                 
        }                                                                                            
    }                                                                                                

    /**                                                                                              
     * Apply any pop animations in the Intent of the given Activity to a pending transition.         
     * This should be used in place of  {@link Activity#overridePendingTransition(int, int)}         
     * to get the appropriate pop animations.                                                        
     * @param activity An activity started from the {@link ActivityNavigator}.                       
     * @see #addPopAnimationsToIntent(Intent, NavOptions)                                            
     * @see #getPopEnterAnim()                                                                       
     * @see #getPopExitAnim()                                                                        
     */                                                                                              
    public static void applyPopAnimationsToPendingTransition(@NonNull Activity activity) {           
        Intent intent = activity.getIntent();                                                        
        if (intent == null) {                                                                        
            return;                                                                                  
        }                                                                                            
        Bundle bundle = intent.getBundleExtra(KEY_NAV_OPTIONS);                                      
        if (bundle != null) {                                                                        
            NavOptions navOptions = NavOptions.fromBundle(bundle);                                   
            int popEnterAnim = navOptions.getPopEnterAnim();                                         
            int popExitAnim = navOptions.getPopExitAnim();                                           
            if (popEnterAnim != -1 || popExitAnim != -1) {                                           
                popEnterAnim = popEnterAnim != -1 ? popEnterAnim : 0;                                
                popExitAnim = popExitAnim != -1 ? popExitAnim : 0;                                   
                activity.overridePendingTransition(popEnterAnim, popExitAnim);                       
            }                                                                                        
        }                                                                                            
    }         

SomeActivity

  val intent = Intent(context, SomeActivity::class.java)
  intent.flags = Intent.FLAG_ACTIVITY_CLEAR_TASK
  context.startActivity(intent)