The One UI 4 beta started pushing out to Galaxy Z Fold3 and Z Flip3 owners in South Korea a few days ago, and now it’s rolling out to US units as well. You must first register for the beta program, which can be done through the Samsung Members app.
Only unlocked phones (as in Korea) are allowed to participate, therefore if you have a carrier phone, you may have to wait for the stable version. Which is probably a smart idea anyway, given beta software isn’t without flaws.
In the United States, owners of the Samsung Galaxy Z Fold3 and Z Flip3 can now participate in the One UI 4 beta program.
Some Z Fold3 owners have already noted that the upgrade breaks the external display’s 120 Hz option, leaving it at 60 Hz all of the time. Samsung is aware of the problem and trying to resolve it.
You may learn more about One UI 4 by watching these videos. The Galaxy S21 phones are also among the first Samsung phones to run the latest Android 12-based software, as previously stated.