Developers can download the new watchOS RC
Developers participating in Apple’s beta program can get the new builds via the Apple Developer Center or more directly by updating their hardware already running the betas via their respective Settings apps. The public beta versions usually turn up shortly after the developer versions, and can be signed up to through the Apple Beta Software Program.
Updates can be triggered automatically or via the Settings app for most of Apple’s hardware with little difficulty for users. For visionOS, users require a registered Apple developer account, though it can be a free account rather than a paid-up one.