The Galaxy Z Fold 3 isn't releasing for ten more days, but Samsung's already rolling out a pre-release software update to its latest and greatest Android flagship. Labeled as the release F926BXXU1AUGB, this particular download seems to be mostly focused on refining the overall user experience. This is pretty much par for the course, as far as pre-release firmware destined for Samsung devices is concerned.
On the security front, the update includes the July 1st, 2021 patch level. If you already pre-ordered a Galaxy Z Fold 3 or plan to buy it day one, that's the security update you can expect the device to run out of the box.
The August update should be ready for you once your Galaxy Z Fold 3 arrives
Of course, it's very likely that Samsung will already have the August 1st patch ready for you to download by the time the device finally makes its way to you. If you aren't in the loop, pre-orders should start shipping by August 27th in most parts of the world. And whenever you do get yours, one of the first things you should do after unpacking it is connect to the Internet – preferably Wi-Fi – then go to Settings > Software update > Download and install.
Doing so will ensure you're running the latest security release right from the get-go. And if you don't mess with the default settings, the smartphone should continue updating itself automatically from there. Beyond that, you should be good for at least four years, if the Galaxy Z Fold 2 is any indication.