Yes, if you opt to leave the Beta program before the full release, you will have to factory reset. If you wait until after it updates to the full release, you can then opt out of the overall Beta program before the next cycle begins (i.e. before Android 13 beta starts) and you will just continue on with the normal update cycle. You could then re-enroll in the next beta cycle if you want to. This is what I usually do when they get to the second or third beta release as I only have this phone and don't want to experiment with first beta releases. Note, when you are in the beta program you will not be getting the monthly updates.