While we don't yet know the new iPhones Apple will be dropping this fall — though there are iPhone 17 rumors — we do know, per Apple's site, that the phones listed below will be compatible with iOS 26. Basically, if you have an iPhone that was announced in 2019 or later, you're in the clear:

Apple has introduced Liquid Glass in its upcoming iOS 26 update. Liquid Glass provides a "see-through" visual of a glassy surface throughout iOS 26's interface. The liquid part comes into play with how the see-through visuals adapt to the screen depending on what the user is doing.