Change Color of IPhone X top and bottom using Xamarin Forms

protected override void OnAppearing()

        {

            base.OnAppearing();

            var safeAreaInset = On<iOS>().SafeAreaInsets();

            BgStack.Padding = safeAreaInset;

        }

You can put your page inside the stacklayout

 

<StackLayout x:Name="BgStack" BackgroundColor="#FF4D4D"></StackLayout>

Helpful link Link1 ,Link2