Do I need an additional adapter to charge my new iPhone 12 Max

You can use an old adapter and charging cable if you have it (usb to lightening). If you have a usc c adapter you can use that with the usb c to lightening cable that comes with the device. Or you can opt to buy a usb c adapter. Of course...you can also opt to use a computer to charge your phone if it has a usb c port or you have a usb to lightening cable.