There is no way to adjust the external camera in any way.
Firs thing I noticed when I got MSFS last year was how the external camera had the plane sitting so far down on the screen that most of the time a piece of it is off the screen completely. It’s really messed up, and can even give me a headache sometimes as it really throws off your sense of balance. Especially as someone with mild OCD it’s really irritating to have everything off center for no reason at all.
I’ve yet to hear any response from the devs or any logical reason at all of why they would force this poor design choice on us without the ability to adjust it. Hoping for a solution to this some day…