iOS 12.1.1 (build 16C50) is an official Apple over-the-air update for the iPhone 8 Plus (GSM), released on 2018-12-05T18:10:04Z. 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: 7e3925cbc36c31f790269955107dfb563e2ca70d.zip.