The Apple x supports 18W of charging power.
The iPhoneX Fast Charge uses the USB PD charging protocol, and Apple is one of the members of the charging protocol alliance. At this stage, Apple's official chargers that can be used by the iPhoneX to support fast charging have five USB-C interfaces: Apple 18W, 29W, 30W, 61W and 87W.
Up to 18 watts fast charge. The Apple X fast charge supports a fast charge of up to 18 watts. This requires you to buy a supported adapter yourself. I'm not supposed to bring the original.