iOS 12.1.3 (build 16D39) is an official Apple over-the-air update for the iPhone 8 Plus (GSM), released on 2019-01-22T18:09:13Z. The update package is 1.5 GB. This is a delta (partial) update that requires 11.4 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 76fc52d7391104a629746511ec5206ae3aa0fe8e.zip.