iOS 14.3 beta 3 and iPadOS 14.3 beta 3 are now available to registered developers, who can get it over the air or through Apple's Developer Center (via MacRumors). If you're a public tester, you should get this update sometime in the next few days.
If you want to try iOS 14.3 before it's released to everyone, you can enroll in the Apple Beta Software Program to become a public tester.
The update to iOS 14.3 brings with it a few notable changes. When you're opening an app with a custom icon that you made with Shortcuts, the app will now open directly rather than first routing through the Shortcuts app, which means the app launch should be much faster. This ought to be a great improvement for folks with custom iOS app icons.
Also included in iOS 14.3 is Apple's ProRAW image format for the iPhone 12 Pro and Pro Max, which lets you shoot in RAW for more editing options but still using Apple's image pipeline data like noise reduction. The update lets you set Ecosia as your default search engine, too, and includes an icon that hints at the design of Apple's much-rumored AirPods Studio headphones.
Apple also released watchOS 7.2 beta 3 today (via MacRumors). This release includes a Cardio Fitness feature as well as support for the upcoming Apple Fitness+ service.