iOS 12.1.2 (build 16C101) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-12-17T21:07:11Z. The update package is 1.35 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: c312a5260a5f5d723a6a5232ac0bcfe53dc0a5b0.zip.