Android: Some apps in Android can enter what's known as "immersive mode" which hides your buttons and status bar, giving you extra space. This Tasker action lets you enable this mode for any app whenever you need it.
The guide below from XDA walks you through how to create an immersive mode toggle. When you tap it, the status bar and on-screen navigation buttons (if your phone uses them) will pull away, leaving that much more screen real estate for you.
You'll need Tasker and the Tasker plugin AutoTools for this to work. You can also use the AutoNotification plugin to add the immersive mode toggle to your quick settings shortcuts. Check out the full guide below for instructions on how to set it all up.