How to get the watch face that's on the Apple Watch box?
Edit 2: watchOS 5.1 does allow you to do fullscreen color watch faces, but the hands do not match the color on the box.

Original: After doing some looking, this watch face simply does not appear to actually exist as an option in watchOS 5.0.

Edit 1: It looks like a similar full screen color watch face exists in iOS 12’s watch face gallery, but it doesn’t work properly on the Apple Watch; it simply shows as a standard numberless dial.