Hi guys, I found a way to start the game in full screen in case anyone is interested.
Only one Boolean variable is needed, and we say that if it is true, we request a full screen and if it is false, we delete the full screen. In this way we can also make the player deactivate this action.
The only thing is that when the game opens, while loading it will remain in a window, but when it starts it will open in full screen.