How do I update my iPhone 6 to the 15 version out now

iPhone 6 is stuck at iOS 12.5.7. That is the end of the update road for the iPhone 6

If you want to run iOS 15, you will need an iPhone 7.

If you want to run iOS 16, you will need an iPhone 8 or higher model.

The iPhone 6 is not capable of running iOS 16. It cannot run iOS 13 or higher.

i don’t know

worawut48 wrote:

i don’t know

While you might not, published information from Apple indicates iPhone 6 is supported on iOS 12, and no later.