hello , wich one charger adapter good for iphone 12 pro max ? 20w or 30 w or more ?

The 20W is what I would get personally. It will fast charge and it is also the one recommended for use with the MagSafe Charger in case you ever want to do that.

See: Fast charge your iPhone - Apple Support and MagSafe Charger - Apple

The Apple 20 W is specifically designed for the iPhone 12 series. The 30 W won’t be any faster. That doesn’t mean you can’t use a 30W or even a 61W MacBook charger, but there is no added advantage to the higher capacity power sources.