Yes... but it can be tricky. At batteryOn the Yaw value is initialized to a value determine by the compass. After that the Yaw value is determined mostly by the IMU (gyros, and accelerometers) with the compass providing corrective inputs at low gain. If Yaw is correct but the AC is then moved to a geomagnetically distorted location the Yaw value will start a gradual change to the incorrect value dictated by the distortion. So it's possible that if launch occurs without delay after moving then Yaw will still be OK.
Your post could be summarized as asking how can it be determined if Yaw is correct before launch. The single most effective method of determining thisis correct is to look at the red triangle heading indicator on the Go App map. If that is inconsistent with the actual heading then Yaw is incorrect. It's almost guaranteed that erratic flight, possibly a fly away, will occur after launch.
This method will always work. If you just gotta launch from concrete just make sure this heading indicator is correct before launch.This method will work in those cases where your P4 is sitting in the middle of a grassy field but unbeknownst to you there is a hidden 1/4 " washer sitting directly below the compass.
Thank you!!!