Question What results do I expect if I make a feature film with SONY a7 3 camera with a bit of color grading that I know?

This all depends not just on the camera but how you shoot it. It's like asking what you can expect if you buy a Prince Tennis Raquet, what you can get out of it depends on how you use it.

Outside of that really obvious thing, it's a good camera so feel free to to what you want with it, results are not from the camera though. You can shoot a good film with a $50 webcam if done properly.