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:

Developers can try out the iOS 26 features starting today through the Apple Developer Program. Public betas of the new operating systems will be available in July. Apple will make iOS 26 and the other new operating systems available this fall, likely soon after its annual iPhone event, which typically takes place in September.