For phones specifically, only a small portion of people are using iPhones older than 5 years. So basically the vast majority of active iPhones are supported by

For phones specifically, only a small portion of people are using iPhones older than 5 years. So basically the vast majority of active iPhones are supported by iOS 12. There’s probably a decent number of active iPads that can’t run this iOS version but that’s probably for the better since the older ones would probably be too slow.