iOS 12.1.3 (build 16D5037a) is an official Apple over-the-air update for the iPhone 6, released on 2019-01-07T18:07:17Z. The update package is 227.14 MB. This is a delta (partial) update that requires 12.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: af03f19f01ee23960b9e71ed1fcab2607b574061.zip.