Arducopter - Heading face Home or next waypoints

WP_YAW_BEHAVIOR: Sets how the autopilot controls the “Yaw” during Missions and RTL.

0 = Never change Yaw.
1 = Face Next Waypoint including facing home during RTL.
2 = Face Next Waypoint except for RTL (i.e. during RTL vehicle will remain pointed at its last heading)

https://ardupilot.org/copter/docs/rtl-mode.html