Do you know where you want to mount your starlink? Do you know where you want to make the connection to the harness? Dash/backseat etc.
Do you have plan for future electrical upgrades?
Full disclosure, I do not currently own a Starlink, my suggestions is based off the paperwork and specs I can find online.
16ga 3ft will be fine for your dashcam. You can probably "
piggy back" off your connection and add usb chargers etc to it.
non-lit adapter/charger
If you plan to make the starlink connection in the back seat area. I would consider the 12ga due to the length as well as potential voltage drop.
If you have upgrades you are thinking about for the future. Consider the 12x2 and terminating in the back seat to a fuse panel. Something like this Blue sea panel.
Blue Sea panel
I know I didn't answer your question. I wanted to offer a few different ideas to you. Maybe 1 will spark an idea for the future.