How to switch from drone to rover section in PX4 Autopilot software

I’m new to PX4 Autopilot software. I looked at the general structure of the software. But I couldn’t see where they changed the airframe part. Since we can change it through QGC, I think we may need to change it directly from within the software. In my project, I want this part to be updated with information that I will send via ROS2 and I want the mode to change.
What I want to kwon is, can we change the airframe directly from within the software without QGC ?

From my understanding, the airframe is able to be configured as a parameter. I don’t know if this is the recommended way, but we have it setup in the rc.board_defaults of our board, like so:

param set-default SYS_AUTOSTART 19001

But looking at the parameter documentation, you’ll need to reboot to apply it. Parameter Reference | PX4 User Guide

Hope this might help. Cheers