iPhone 15 pro Charger 18w or 20w

I bought an iPhone 15 pro, now I'm trying to figure out if I should buy a new 20w charger or if I can use the one I own from my iPad Pro 11 (2019), 18w charger (A1692).

The strange thing is that I can't find anything to clarify this point,

Apple states on the site that you can use any charger greater than 20w

On another page instead mentions the 18w charger as usable, but reading deeper it brings back the 18w A1720 charger and never A1692

WHAT DO YOU THINK ? AND WHAT CAN YOU REALLY USE TO CHARGE IPHONE 15 PRO SAFELY?