https://www.techradar.com/news/apple-launches-ios-12-public-beta-today-to-speed-up-your-iphone-and-ipad

Apple's iOS 12 public beta is now available to everyone with a willingness to test the new software on their iPhone and iPad.

Its big highlight is that it'll make your older devices faster, according to Apple. The iPhone 6 Plus, for example, is 40% faster at launching apps, 70% faster at launching the camera app, and 50% faster at displaying the keyboard.