iOS 12.1 (build 16B5084a) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-10-15T17:03:27Z. The update package is 170 MB. This is a delta (partial) update that requires 12.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 7a9e311f73dc9ea10e6b7a25e8ddc9155b43ef55.zip.