I assume you're using React Navigation for navigation on the react native app.

Here's a demo code block to configure header background.

export default function App() {

  return (
    <NavigationContainer>
      <Stack.Navigator>
        <Stack.Screen
            name="Home"
            component={HomeScreen}
            options={{ title: 'Demo', headerStyle: {
              backgroundColor: '#000000'
           } }}
        />
      </Stack.Navigator>
    </NavigationContainer>
  );
}