There’s a help menu right at the top of the screen. In every app it will search the menus and provided application help. In the finder, it also has a “macOS hel

There’s a help menu right at the top of the screen. In every app it will search the menus and provided application help. In the finder, it also has a “macOS help” item which brings up the offline user manual, including the table of contents where you will find the entry “Apps -> Work with app windows -> Maximize or minimize app windows”