watchOS 6.3 (build 17U216) is an official Apple over-the-air update for the Apple Watch Series 3 (38mm, LTE), released on 2021-01-26T18:26:22Z. The update package is 219.19 MB. This is a delta (partial) update that requires 6.2.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a94e048a5bd81f5f81423976231af0761cd1a35e.zip.