How do I install IOS 26 on my IPhone 6S?

Jack4809 wrote:

How do I install IOS 26 on my IPhone 6S?

You do not install iOS 26 on your iPhone 6s. The iPhone 6s ran iOS 9.0 when Apple introduced it in September 2015. It got six major iOS updates, and you can update it to the latest release of iOS 15. You cannot update an iPhone 6s to iOS 16, 17, 18 – or 26. (26 isn't even out yet except in developer beta test form.)

As for the iPhone 8 Plus mentioned in your tag line, you do not install iOS 26 on it, either.

You go buy a phone which will get iOS 26 in the fall when it is released. Your iPhone 6S is forever locked on iOS 15.8.4. You should have gotten a hint it was done with major updates when it couldn't get iOS 16, iOS 17 or iOS 18. It certainly WON'T get iOS 26.

An iPhone 6s, iPhone 6s Plus, iPhone 7, iPhone 7 Plus, or iPhone SE 1 isn't capable of 16 or above; they require an A11 or better CPU.

(260559)

You cannot. Refer to your developer program guidelines for hardware requirements, developer.apple.com