Try using Command-Control-F to toggle between full-screen and normal view.
In most apps, those that follow Apple's guidelines, while in full-screen mode you can also move the cursor to the very top of the screen. At that point the menubar should appear. At the extreme right end of the menubar will be a blue rectangular icon - click it, and the view should revert to normal view.
Esc should also work, according to Apple's descriptions of full=screen mode - however, some apps might grab the Esc key for their own uses, and it may not then be available for this use.