https://wccftech.com/how-to-download-ios-12-beta-4-without-developer-account/

iOS 12 Beta 4 is out for developers, and here’s how you can download it without an Apple Developer Program account right away.

iOS 12 Beta 4 packs in some bug fixes, some visual changes and performance enhancements. And as usual, the new beta is available for developers only for now. Needless to say that the changes packed in today’s beta will eventually be available to those enrolled in the public beta testers program, but what if you want all that goodness right now? If you are on iOS 11, then you are in luck.