QGroundControl Joystick servo control

hello everyone. If anyone has succeeded in doing this, I would appreciate any help.
I want to control it with a joystick via Mavlink. But I can’t see any action that can control the servo added in QGroundControl. So I tried to see if I could control it using the Gimbal action and the result was a failure.
If anyone has had success with similar work, please share some knowledge. thank you.

If you are the control allocator then it is pretty easy: Payloads and Cameras | PX4 User Guide

Just map your servo to Offboard Actuator Set 1 (up to Offboard Actuator Set 1) and then use MAV_CMD_DO_SET_ACTUATOR

Thank you for your kind reply.
Sorry for the rudimentary question.
If I want to use MAV_CMD_DO_SET_ACTUATOR, how should I assign it in the joystick settings?
I couldn’t find any option for actuator control in the joystick button assignment.
Is there a separate extension option? Or do I need to fix something?