Press F1 then select start in fulscreen, then restart game.
All RPG maker games can do it, but dont forget the keybind it's really hard to get out of the fullscreen because it hides your mouse and you cant "rightclick" to get the options bar without the keybind afterwards.
And it is a setting for all RPG maker games at once.
Or you can go into the game.ini file in the root folder of the game and change Fullscreen=0 to Fulscreen=1, then it's a game specific option.