Apple has seeded Release Candidates of iOS 15.3, iPadOS 15.3, tvOS 15.2, watchOS 8.4, and HomePod software 15.2 to developers and public beta testers for testing.
Malcolm Owen for AppleInsider:
The latest builds can be acquired by developers in the beta-testing scheme via the Apple Developer Center, or as an over-the-air update for hardware already using earlier beta builds. A public beta version of the releases is… available through the Apple Beta Software Program website.
For the moment, the betas for iOS 15.3 and iPadOS 15.3 offer no real major feature changes to report on, and so far appears to be a maintenance release that focuses on performance and bug fixes. More features may surface as builds get provided to testers.