https://techcrunch.com/2018/07/18/apple-releases-third-ios-12-beta-to-everyone/

Apple just released the third version of the iOS 12 beta as part of the public beta program. It means that everyone can now install a development build of iOS 12, the next major version of the operating system for iPhone and iPad.

Don’t forget this is still a beta version. Things will crash, things won’t work. Don’t be surprised if you lose data in your Photos, Notes or Messages apps for instance.