react-native-navigation/android/app/src/main/res/values/styles.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <style name="Modal" parent="@android:style/Theme.Translucent.NoTitleBar">
        <item name="android:windowAnimationStyle">@style/modalAnimations</item>
    </style>

    <style name="modalAnimations">
        <item name="android:windowExitAnimation">@anim/slide_down</item>
    </style>
</resources>