react-native-template-mrf/project/asset/splash_screen.xml

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:drawable="__background__"/>
    <item>
      <bitmap 
        android:gravity="center" 
        android:src="@mipmap/logo"/>
    </item>
</layer-list>