Question about updating/debranding

I didn't know where to post this

just one question i understand that if i flash or update a phone i will lose data store on that phone
does this mean that if i updated or debranded a network unlocked phone it will reset back to the original
network it was at when i bought it?

When update via SEUS - all in phone memory will be erased.
Debranding is same ... again all in phone memory will be erased.
If is full unlocked (not unlock patch unlocked) - you can debrand/update your phone without reset back to the original network.