https://www.theguardian.com/technology/2018/jun/26/ios-12-how-to-install-apples-latest-iphone-software-right-now

Apple’s new faster update with anti-smartphone addiction features is now available to test for the iPhone 5S or newer

Apple has released the public beta version of the much anticipated free iOS 12 software update for iPhones and iPads, which means those eager to try it before anyone else can install it right now.