iOS 12.1.2 (build 16D5024a) is an official Apple over-the-air update for the iPhone 6s, released on 2018-12-10T18:09:10Z. The update package is 267.8 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: c47fa8bfde1282cfc77ca880e1ff34f5a71c292e.zip.