The peak charging power of the iPhone EXs Max can reach 9V*2A=18W, and the charging power will change with the increase of electricity. Whether it is PD18, PD30...... Charging the iPhoneX Max is the same power, so the charging speed is about the same. As for how to choose the charger depends on your use of the device, if it is only for iPhone8 series and ipad Pro, then choose PD 18W on the line.
If you want to charge the MacBook and MacBook Air in addition to the iPhone and ipad Pro, choose the PD30W
Supports 18w fast charge
The iPhoneX supports PD fast charge, which is around 18W. The iphonex was released on September 13, 2017, Beijing time, and according to the official introduction, it can be charged to 50% power in 30 minutes, requiring the use of 18W or more power adapters. The iPhoneX Fast Charge uses the USBPD charging protocol, and Apple is a member of the charging protocol alliance.