iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 8 (GSM), released on 2019-01-22T18:09:07Z. The update package is 284.5 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: 16db0a5473383cb312bd89aead6e5382a962d9af.zip.