AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.nisaefendioglu.example">

    <application>
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
            </intent-filter>
        </activity>

        <activity-alias
            android:name=".FirstAppIcon"
            android:enabled="true"
            android:exported="true"
            android:icon="@mipmap/first"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/first"
            android:targetActivity=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity-alias>

        <activity-alias
            android:name=".SecondAppIcon"
            android:enabled="false"
            android:exported="true"
            android:icon="@mipmap/second"
            android:label="@string/app_name"
            android:roundIcon="@mipmap/second"
            android:targetActivity=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity-alias>

        <activity-alias
            android:name=".ThirdAppIcon"
            android:enabled="false"
            android:roundIcon="@mipmap/third"
            android:exported="true"
            android:icon="@mipmap/third"
            android:label="@string/app_name"
            android:targetActivity=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity-alias>
    </application>

</manifest>

MainActivity.kt

package com.nisaefendioglu.example

import android.content.ComponentName
import android.content.pm.PackageManager
import android.os.Bundle
import android.view.View
import androidx.appcompat.app.AppCompatActivity
import com.nisaefendioglu.example.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {
    private lateinit var binding: ActivityMainBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)

        initialize()
        handleClickEvents()
    }

    private fun handleClickEvents() {
        binding.btnFirst.setOnClickListener {
            setIcon(ICON_NUMBER.FirstAppIcon)
        }
        binding.btnSecond.setOnClickListener {
            setIcon(ICON_NUMBER.SecondAppIcon)
        }
        binding.btnThird.setOnClickListener {
            setIcon(ICON_NUMBER.ThirdAppIcon)
        }
    }

    private fun setIcon(targetNumber: ICON_NUMBER) {
        for (number in ICON_NUMBER.values()) {
            val action = if (number == targetNumber) {
                PackageManager.COMPONENT_ENABLED_STATE_ENABLED
            } else {
                PackageManager.COMPONENT_ENABLED_STATE_DISABLED
            }
            val componentName = ComponentName(packageName, "${packageName}.${number.name}")
            packageManager.setComponentEnabledSetting(componentName, action, PackageManager.DONT_KILL_APP)
        }
    }

    private fun initialize() {
        binding = ActivityMainBinding.bind(findViewById<View>(android.R.id.content))
    }

    enum class ICON_NUMBER { FirstAppIcon, SecondAppIcon, ThirdAppIcon }
}

settings.json

{
  "birthdayIconEnabled": true,
  "birthdayIconPath": "birthday_icon.png"
}