Last week, Apple released iOS 13 and watchOS 6, its newest major updates. And while we know that iOS 13.1 is going to arrive tomorrow, the firm released the first developer beta for watchOS 6.1 today. There's not a lot that's new, but the release notes do say that there might be some compatibility issues with Xcode, so you'll want to grab the next Xcode beta release when it's out.
If you were on the watchOS 6 beta, you should receive this update as an OTA. If you don't want it, then you should uninstall the configuration profile immediately. Remember, unlike all of the other operating systems that Apple runs beta software for, you can't easily roll back an Apple Watch to a stable version of the OS.
Also available today is macOS 10.15 Catalina Developer Beta 9, which presumably includes a few bug fixes while Apple prepares for general availability. That's slated to arrive in October, but we should see a GM seed first.
It's unclear when watchOS 6.1 will arrive, probably around the same time as iOS 13.2, which will likely be in beta testing a few days after iOS 13.1 is released tomorrow.