You are going to have to look that up to get the whole story but basically the drone will transmit various details about itself, its pilot and positions of both.
Looking at the RC2 specifications, the only reason that it would need connection to a phone would be to give it internet connection. Disabling mobile data (not near a wifi connection) would sever that.
If you want to fly a mini 4 pro you have to use DJI fly.
If you want to use waypoints the remote needs to know where you are. There is also the waypoint flights in the cloud facility that you might use.
I fly with an RC2, it may be connected via...