Hey IOS, My question is how I can update my phone. I am with IOS 12.5.6

At 12.5.6 your iPhone 6 is already running the highest iOS that is currently available that will run on it. Since iOS 12 is no longer supported you likely won't be seeing any future updates.

An iPhone 6, or any other unit on 12.5.6, isn't capable of 13 or above.

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