You need to use a USB 3.0 Type C to Lighting cable with PD with the wallcharger, im using this one...

Fast Charging USB C to Lightning Cable, Metrans 3FT/1M USB Type C to Lightning Cable for iPhone X iPhone 8/8Plus Connect to Macbook https://www.amazon.com/dp/B0769RSL5M?ref=yo_pop_ma_swf

This is the wallcharger that im using with the cable...

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F401445890265

Tha cable needs to be type c to ligthing with PD This one works well

Fast Charging USB C to Lightning Cable, Metrans 3FT/1M USB Type C to Lightning Cable for iPhone X iPhone 8/8Plus Connect to Macbook https://www.amazon.com/dp/B0769RSL5M/ref=cm_sw_r_cp_api_ea8kAbMVED5MY

My wallcharger doesnt even have PD, it is a Lumsing USB 3.0 48V with Type C... the cable need to have de PD Protocol