iOS 12.1.1 (build 16C50) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-12-05T18:10:20Z. The update package is 289.9 MB. This is a delta (partial) update that requires 12.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 54a0179614792724d9a122ba73ad2a11b27db125.zip.