What charger can I use for iPhone 12 pro max?

5V=3A/9V=2A/12V=1.5A

Many USB chargers can output more than one voltage, but they always start at 5 volts, and only output the higher voltages if the device being charged tells the charger that higher voltage is OK. Any USB charger should be OK if used with a USB to Lightning cable.

if the connector fits and the charger does not output higher than 5volts you can use it

if it output higher than 5volts it will toast the ios device

5V=3A/9V=2A/12V=1.5A

is not something it can output at the same time, but if it output 9 or 12volt it will toast the iphone