iOS 12.1 (build 16B5089b) is an official Apple over-the-air update for the iPhone 6s+, released on 2018-10-22T17:02:07Z. The update package is 461.8 MB. This is a delta (partial) update that requires 12.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 541f1bfe6b4aa5a895f51466e2f7d7c1c8af6049.zip.