If someone is on 13.0b8 and did not delete the profile, they will see 13.1b3. If they first delete the profile, they will see no updates. The GM will only appear on 19 Sep.
One way to load up 13.0GM now is to use 3utools with the ipsw file, if on windows and still on 13.0b8. I’ve successfully upgraded mine from 13.0b8 to 13.0GM via this method. For Mac users, just have to download the ipsw file and option click update in finder.
If you’re already on 13.1b3, there is a way to do it too. Got to back up, 3utools restore to 13.0GM, modify a file in the backup and restore the backup. I’d suggest just wait for 13.1GM.