This article explains how to enable immersive mode on Android. Instructions apply to smartphones and tablets running Android 4.4 KitKat or later.
How to Enable Immersive Mode on Samsung Phones!
There are a few programs that allow you to use Immersive Mode in any app. A free option is the Fullscreen Immersive app from PhotoSafe.
Download the PhotoSafe Fullscreen Immersive app from the Google Play Store.
Launch the app and tap I agree.