The React native app, I am working on is not taking the entire viewport like every other app. I tested it on an iPhone 11 pro and it still gave space at the top and bottom.
I don’t think this is a CSS flex, height declaration, or SafeAreaView issue. It is about the height the app itself is taking. See the below picture gotten from returning the code in App.js.

<View style={{flex:1}}>
  <Text>XXX</Text>
</View>