https://wccftech.com/download-ios-15-and-ipados-15-rc-for-iphone-and-ipad-released/

The iOS 15 and iPadOS 15 RC download for iPhone and iPad devices is now available for developers and testers.

Before you go ahead, it is important to know that this is potentially the final release of the software but meant for developers and public beta testers. If this turns out to be a bug-free release with no issues whatsoever, then Apple will go right ahead and publish this update to everyone else with a compatible device around the globe in a couple of weeks time.