Before you answer "hold the volume button", I am asking about a Surface laptop that has no external power/ volume buttons. (not the tablet) I have tried using the F6 to no avail.
I want to be able to boot to USB.
Boot to the UEFI and change the boot order and drag USB to the top of the boot order list.
Full instructions at How to Configure Surface Laptop 3 UEFI/BIOS Settings | SurfaceTip