Apple today seeded the first beta of what would become the third major software update to iOS 10 since its September 2016 release. The release includes a new Find My AirPods feature and other enhancements, like Reduce Motion for websites.
iOS 10.3 beta 1 (build 14E5230e) is available to registered developers who are members of Apple Developer Program. A version of the software aimed at public beta testers registered with Apple Beta Software Program is expected shortly.