20w maximum
https://www.apple.com/my/iphone-12/specs/

no wrong... even you try with charger adaptor 60W also max 20W, the device itself should only draw 20W max, you have 200W charger still 20W the device will draw, so it is up to 50% charge in 30 minutes, no mater how many watts charge you use, anything above 20W, same 30minutes to 50%

but i doubts Apple change it to max 20W, i believe it is still 18W max, just they are selling 20W charger now... because if like previous gen 18W compare to 20W, to 50% could takes lesser than 30 minutes

anything have to wait someone get iPhone 12 on hand and try out