https://wccftech.com/download-ios-16-beta-without-dev-account/

You can download iOS 16 beta, iPadOS 16 beta and watchOS 9 beta on iPhone, iPad, Apple Watch for free.

In case you haven’t noticed, iOS 16, iPadOS 16 and watchOS 9 beta is now available for download. It’s for developer only and the public beta will become available in a short while. If you want to test out the new software on your compatible iPhone, iPad or Apple Watch, then you need to pay Apple $99 and sign up for the Apple Developer Program.