iOS 12.1.2 (build 16C101) is an official Apple over-the-air update for the iPhone 6s, released on 2018-12-17T21:07:00Z. The update package is 1.29 GB. This is a delta (partial) update that requires 11.3.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 35492ad05d604b29605261290de20b2d204d8fad.zip.