It looks like iOS 15.2.1 isn’t the only version of iOS that Apple has released today. Apple has also seeded iOS 15.3 beta 2 to developers who have been beta testing iOS 15.3 on their test devices.
The build number for iOS 15.3 beta 2 is 19D5040e. Alongside iOS 15.3 beta 2 Apple has also released iPadOS 15.3 beta 2, watchOS 8.4 beta 2 and tvOS 15.3 beta 2 to developers.
If you are beta testing any of these operating systems on your test devices, then you can download them over-the-air through the Software Update section of their respective devices.
iOS 15.3 and other releases are minor updates and do not contain any major new features that you should get excited about.
Having said that if you are a developer who is beta testing iOS 15.3 on his or her devices and you are able to find any noticebale changes, then do share with us in the comments below.