How to upgrade my iPhone 6 iOS from 12.6 to 14.0

Hello,

An iPhone 6 (or 6 Plus) will only update as far as iOS 12.5.7. To ensure you have at least that, you can try updating your device. 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 won't offer to install anything. If you want to run a higher system version than your current device will support, you need to buy a newer device.

This support article has instructions about updating your iPhone or iPad wirelessly --> Update your iPhone or iPad - Apple Support

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

The iPhone 6 can update as far as iOS 12.5.7......but that is the end of the update road for the iPhone 6.

Reason....the iPhone 6 cannot meet the requirements to run higher iOS versions.

iOS 14 is no longer available.

You will need an iPhone 7 to run iOS 15. If you want to run iOS 16, you will need an iPhone 8 or higher model.