iOS 10.3 beta 3 with Find My AirPods and other enhancements and macOS Sierra 10.12.4 beta 3 with Night Shift Mode and other perks are both now available for public beta-testing, assuming you’ve enrolled in Apple’s Beta Software Program. After signing up on the web at beta.apple.com, deploy a special configuration profile on your iPhone, iPad, iPod touch or Mac and you’ll be able to install the latest beta over-the-air via Apple’s standard Software Update mechanism.
Apple today released a second beta of an upcoming iOS 10.1 software update and a third beta of an upcoming macOS Sierra 10.12.1 software update to non-developers who are enrolled in the official Apple Beta Software Program.
Both macOS Sierra and iOS 10.1 public betas can be downloaded over-the-air through Apple’s Software Update mechanism on devices enrolled in the beta program. iOS devices must have the proper certificate installed to run public betas.