Always show AppBarLayout elevation regardless of state

appbar_always_elevated_state_list_animator.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
    StateListAnimator which sets elevation for all states of an AppBarLayout
    Modified from https://github.com/material-components/material-components-android/blob/master/lib/java/com/google/android/material/appbar/res/animator-v21/design_appbar_state_list_animator.xml
-->
<selector xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:state_enabled="true"
        app:state_liftable="true"
        app:state_lifted="false">
        <objectAnimator
            android:duration="150"
            android:propertyName="elevation"
            android:valueTo="@dimen/design_appbar_elevation"
            android:valueType="floatType" />
    </item>

    <item android:state_enabled="true">
        <objectAnimator
            android:duration="150"
            android:propertyName="elevation"
            android:valueTo="@dimen/design_appbar_elevation"
            android:valueType="floatType" />
    </item>

    <item>
        <objectAnimator
            android:duration="0"
            android:propertyName="elevation"
            android:valueTo="0"
            android:valueType="floatType" />
    </item>

</selector>

MyFragment.kt

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
   // ... inflate layout ...
   appBarLayout.stateListAnimator = AnimatorInflater.loadStateListAnimator(context, R.animator.appbar_always_elevated_state_list_animator)
}