All magnetic USB-C to Lightning cables are unable to obtain the specific C91 chip that is needed to support PD charging of 18W. Only the official USB-C to Lighing cable from Apple is able to achieve this. Althought the UNO is unable to support the full 18W, it can still handle a max of 9.75W (9V/1.65A), which is considered fast charging as it is above 9W.
If you are charging your iPhone X or an earlier model with the original Type A cable that comes with the phone, UNO will charge it at the same max speed. However at this point, it is unable to support Apple Fast Charge for Apple Lightning mobile devices such as iPhone X as they require a special USB-C to Lightning Cable that has a C91 chip in it. All magnetic USB-C to Lightning cables are unable to obtain the specific C91 chip.