Not that I think it should be done, but since the drone is carrying the phone, you could have the phone save a GPS point of where you are standing, and then the phone guides the drone away from that point to photograph toward it.

Depending on GPS accuracy in the phone it could work well. GPS waypoint missions are already well established in the drone world.

an actual FPV flight hobbyist 5" prop size class quadcopter (such as you might fly with goggles and a real remote control) can typically carry a gopro hero8/9/10 but a gopro is also a lot more compact, brick shaped, rugged, and has very extensively researched video stabilization systems in gopro's proprietary "hypersmooth" which writes the stabilized video into the HEVC file it records.

putting something flat and large like an iphone on a 5" FPV quadcopter would be awkward and bad.