iOS 12.1 beta 1 ipsw for iPhone,iPad was just released now. And it also includes support for all the ipads models as well.
You can now download iOS 12.1 developer beta 1 ipsw files for iPad models. Including the 2018 version. And install it without a developer profile or UDID. Asking for activation.
Get the latest iOS 12.1 beta ipsw files for ipad models, from the links below. And get it free for your iPad .Without UDID or Developer account. Enjoy before upgrading and check wether it is worth it for you and your phone or not.