Change the default behavior of function keys
By default, to use a function key in a VoiceOver command, you must also press the Fn key. You can change this default behavior so that you don’t have to press the Fn key for VoiceOver commands.
Choose Apple menu > System Preferences, click Keyboard, then click Keyboard.
Select the “Use all F1, F2, etc. keys as standard function keys” checkbox.
Some keyboards have dedicated keys for Home, End, Page Up, and Page Down. These are important VoiceOver navigation keys. If you use a keyboard that doesn’t have these keys, use the arrow keys with the Fn key for these actions.