Recall that iOS 12 Beta 3 is a beta for developers. iOS 12 will also be released soon for users registered in public beta soon, while the release of the final version will take place in the Fall, most likely in September.
Here are all the main news of iOS 12 Beta 3:
This beta is strictly for developers. However if you are curious and want to give it a try, we recommend you download the Apple public beta profile, which is intended for all types of users, but it does not guarantee much less the performance, stability or full functionality.