iOS 12.1 (build 16B92) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-10-30T17:17:12Z. The update package is 1.38 GB. This is a delta (partial) update that requires 11.2.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 023f0b0ff8ca6ba37243e62edcdbb63c77726c07.zip.