Booting from an external ssd dell 7630

Hello. I have a new laptop and want to use it with Linux and windows.
It has one SSD internally. My not original Idea was to have one os{ubuntu} on an external drive and one{windows} in the internal one. make the usb c port the first to search for boot. and if it is not plugged in skip to the internal one. I can’t see anything in the bios to set the port for boot. just the os. when the external drive is not connected and ubuntu is first in line the laptop can’t skip to the windows boot loader.
Thanks and happy new year.