The iPhone X is an Apple product introduced in 2017 that comes with the heirloom 5 volt amp 5 watt charger. At the same time, this mobile phone also supports fast charging, it supports 18 watts fast charging users, 5v3a charger can charge it, but its charging speed can not reach fast charging, just a little faster than the general charging, it is expected from 0 to 100 May take about an hour and a half to be full.
The IPhone x does not currently support 5v3a for charging, because this phone currently only supports the official charging of up to 10 watts, but if you use the official protocol for fast charging, you can choose a higher charging protocol