iPhone X screenshot support in iTunes Connect.
You can now upload screenshots for iPhone X. You’ll see a new tab for 5.8-inch displays under Screenshots and App Previews on your iOS app version information page.
Note that iPhone X screenshots are optional and cannot be used for smaller devices sizes. 5.5-inch display screenshots are still required for all apps that run on iPhone.
iPhone X Screenshot Resolutions
1125 by 2436 (Portrait)
2436 by 1125 (Landscape)
Learn more about uploading screenshots in iTunes Connect Developer Help.
Learn about updating apps for iPhone X.