How to update an iPhone 6?

Hello,

There are different ways to ensure the highest iOS that your device will support is installed on your device. Unfortunately the forum software does not let you report if the device is actually running iOS 12.5.7, just that it is running 12-something. Here's how you can check and update (if possible) at the same time:

This support article has instructions about updating an iPhone or iPad wirelessly --> Update your iPhone or iPad - Apple Support Read the article for recommended criteria for being able to use wireless updating.

You can also use Mac and PC computers to update system software --> Update iOS on iPhone - Apple Support

When updating, your device will update to the highest version currently available that it will support, or it will just say it is up to date (and can't go any higher) and won't install anything. If you want to run a higher system version than your current device is capable of running, you need to buy a newer device.

Any equipment currently running iOS 12.5.7 can't be updated to anything higher.

An iPhone 5S, 6, or 6plus, will only update to iOS 12.5.7

The iPhone 6 cannot update further then iOS 12.5.7 due to hardware limitations. That iPhone is too old to update any further. If you require a newer iOS version, you will require a newer iPhone