iOS 11.3 (build 15E216) is an official Apple over-the-air update for the iPhone X (GSM), released on 2018-03-29T17:11:33Z. The update package is 781.74 MB. This is a delta (partial) update that requires 11.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: accf3b029e676fd84909dc1e92e1d99e282b18c0.zip.