If you're only after a power adapter for your X1C6 + iPhoneX then this Anker device will certainly work. I would however wonder if you really need 100W power, 75W would seem sufficient.

Edit: if you plan to use a USB to lightning connector for your iPhone X then indeed the 100W is needed as apparently this device splits power evenly (50W+50W) between the two USB C. A comment however says it's not fast charging the iPhoneX when they are both used, so now I understand your dilemma.