Should I buy a 20W or 30W charger for my iPhone 16 Pro Max?

If you want to charge it wirelessly with a magSafe Charger, use a 30 watt or larger. Otherwise (i.e., with a USB-C cable), a 20 watt or larger. See: Fast charge your iPhone - Apple Support

Hello~ Either. I have my iPhone charging on an 87W right now with no issues. Click on below and review…

About Apple USB power adapters - Apple Support

Also you may enjoy this user tip authored by *Lawrence Finch*…

When to charge your iPhone or iPad - Apple Community

~Katana-San~