9to5Mac reported the release candidate builds of iOS 27, iPadOS 27, macOS Golden Gate, watchOS 27, tvOS 27 and visionOS 27 going out within hours of the keynote ending, and all of them go to everyone on Monday, September 14. An RC is meant to be the build that ships, though Apple can still push an RC 2 if a late bug turns up. Developers and public beta testers can install them from Software Update on each device.
The September event always carries software Apple held back from WWDC, which is why the RCs land on this day every year. watchOS 27 is the case in point. Apple detailed changes during the Apple Watch segment that it never mentioned in June, and they are already in the build: Workout Buddy now works on the watch with no iPhone nearby, there is a Dynamic app grid built around Siri suggestions, and Find My is one app again. Siri AI on the watch needs an iPhone that supports Apple Intelligence, which means an iPhone 15 Pro or later. On Vision Pro, visionOS 27 turns panorama photos into environments and curves app windows around you.