I tested the "TapFly" function and enabled me to control the camera during the trip using the right stick.

But the control of the camera is very sensitive. Does anyone know how to decrease sensitivity?

Just adjust and turn down the camera gimbal parameters in the settings (DJI GO app). You can tweak almost every parameter individually on both aircraft and gimbal. I have mine to almost the lowest settings on both to get a smooth motion when I film.

My gimbal settings are set to be smooth as well. They are only sensitive when I operate the camera using the right stick while the drone is in the TapFly function.