Nice list from Charlie Sorrel:
The Option key (sometimes marked ⌥ on your Mac’s keyboard) offers you extra options, whether you’re using the keyboard or the mouse.
Remember that keystroke. It’s gold.
Option-clicking on these icons gives you far greater control of some of your Mac’s core functionality… When you do so, a different menu will appear (or at least an augmented version of the standard menu). In those new menus, you will see extra options.