https://wccftech.com/these-are-all-the-devices-compatible-with-ios-12-beta/

Here’s a list of all the iPhone, iPad and iPod touch devices compatible with iOS 12 Beta. Only 64-bit devices are supported, obviously.

iOS 12 is finally here, at least the beta is. The final software will be available to download later this year. But you can find out right now all the devices compatible with iOS 12. Surprisingly, the list carries over from the iOS 11 era which means 64-bit device are covered under the iOS 12 Beta umbrella.