Model aircraft fly in the same way as full-size ones do. The big difference being that radio controlled models are controlled from the ground with a radio transmitter. Power can be by electric motor, 2-stroke or 4-stroke glow or gasoline engines, or in the case of an unpowered glider, by using gravity!
In the model is a radio receiver that receives instructions from the transmitter and in turn runs electric motors called servos. The servos move the control surfaces of the plane causing it to react to the pilot’s inputs from the transmitter on the ground.