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 announced in June that the release of iOS 26 would first appear as developer betas as usual, with the first public beta set for July. When it reaches general release it will be on the 2025 releases, iPhone 17 series, as well the iPhone 16 series and plenty of much earlier models.

Assuming you're enrolled in the Apple public beta program, you can now grab the public beta directly on your iPhone. Just go to Settings, tap on General and select Software Updates. On that screen, tap on Beta Updates to find the iOS 26 beta.