How can update my iphone 6 at 15.5?

The standard iPhone 6 cannot run iOS 15. Supported devices are from iPhone 6S and up.

iPhone models compatible with iOS 15.5 - Apple Support

___Bubba___ wrote:

The standard iPhone 6 cannot run iOS 15.

What do you mean by "standard" iPhone 6? To the best of my knowledge, there is no such thing as a "non-standard" iPhone 6 that is able to run iOS 15.

I simply used the word "standard" as a way to distinguish the iPhone 6 from the iPhone 6S. The iPhone 6 cannot run iOS 15, while the iPhone 6S can.

It's a somewhat confusing usage as they are two entirely different model phones. The 6S is not a version of the iPhone 6.

I understand that. My word choice was only done to reduce the possibility of confusion.

Thank you for your clarification.