If you were to Google Starfield open beta right now, not only would you not find anything official related to the game, but you would see at the top of the search page a sketchy-looking website.
If you go on that website (and we highly recommend that you don't), you may begin to spot some very obvious signs that this is not legit at all. Just make sure you don't click on the download button for the fake beta, as that is surely going to leave you with some dangerous malware.
There's been no mention of a Starfield open beta from the team at Bethesda, but it doesn't seem like an impossible thing to come in the future. We've got plenty of time until September, but even if a Starfield beta is possible somewhere down the line, it's not here yet, and the site called bizongrow dot com is certainly a scam.
Thanks, PC Gamer.