On any Windows based system I've every touched the Windows Key is on the lowest row of keys, on the left, and very often the third key in (after a CTRL and FN key).
Any command for the browser must be done after the browser is open and its window has focus. And WinKey+Up Arrow does maximize the window.
This is not, however, a browser specific command, but a Windows command. Any window that happens to have focus will be maximized if you hit WinKey+Up Arrow, and will be restored down (not minimized to the system tray) if you hit WinKey+Down Arrow.
The list of Windows 10 (and other versions, too) Keyboard Shortcuts can be found at:
Brian - Windows 10 Pro, 64-Bit, Version 2004, Build 19041
The purpose of education is not to validate ignorance but to overcome it.