If you are asking if you can fly a mission with the drone flying along a path in one direction and the entire drone is turned such that the camera is still facing to the front of the drone but the camera is pointed away from the path in which the drone is flying but keeping a fixed angle...then, yes it is possible and I have done it. Don't remember how. But it's not by using a POI because as you know, if you fix on the POI then the angle will change as the drone moves along the flight path.
For example, somewhat like this "manual" flight?
Not my video:
ETA: after thinking more about it, I cannot be sure but maybe I did set a POI for the camera to focus on but it was so so far away that the angular rotation was negligible. I'll have to go back and check.