Press F12 to get to the one-time boot menu. Note that there’s a known issue where sometimes this menu won’t show up if you select “reboot” from your installed OS. You may have to fully power down, wait ~30s then turn the laptop back on while pressing F12.
PS: On my framework I can never remember if my Fn is locked or not so I rapidly cycle between Fn+F12 and only F12 to get to the one-time boot menu.