12 June 2019
UPDATE (March 29th, 2019):
Apple has now released watchOS 5.2.1 developer beta which is the first beta. There is no changelog known for it yet but considering that it is not a significant version number bump, it is likely to be filled with bug fixes and under the performance improvements.
Other than this, iOS 12.3 and tvOS 12.3 public betas have also been released which can be installed by public beta testers. The changelog for public beta is same as the developer beta which is mentioned below.
Original (March 28th, 2019)
Apple and software updates have become almost synonymous considering the lightning fast speed at which updates are rolled out. It was just a few days back that Apple used its Showtime event as a launchpad for its final and stable version of iOS 12.2. You may have already guessed it by now, the company has released the first beta of iOS 12.3.
As usual, iOS isn’t the only Apple platform which receives love in the form of timely software updates. Along with the first beta of iOS 12.3 with the build number 16F5117h, the company has also released tvOS 12.3 and the first beta for Apple TV Software 7.3. In almost all probability, similar betas will be shortly released for macOS and watchOS. The latest beta builds are available for developers through and over the air update or through the Apple Developer Center.
As of now, it’s too early to tell what exact changes these betas bring. However, once the release notes surface, a deeper analysis can be made. However, as a rule of thumb, most beta updates come with minor bug fixes and system improvements. It’s always advisable to never jump to the latest beta especially if it's your daily driver as betas may fix things but in doing so may also break things and open up a can of worms!