Why no update my iphone 6 because no i have apple id

Settings > General > Software Update. Your phone will tell you if you have an update. If it is currently at 12.5.7, you will not be able to update any further and will need to purchase a new phone.

The iPhone 6 cannot update further then iOS 12.5.7 due to hardware limitations. That iPhone has too old hardware to update any further

There is no update for the iPhone 6.

melrhon wrote:

Can you send me link please, i don't no how to upate.

If your iPhone 6 is running iOS 12.5.7, you are current.

If you have apps requiring a newer iOS version, then those apps also inherently require a newer or new iPhone.