I will be receiving my new iPhone 13 max tomorrow. Tell me about the charger I should purchase for it.

In addition to the above: Fast charge your iPhone - Apple Support

The cable you will get is USB-C to Lightning, and will require a USB-C charger.

For existing chargers, you can acquire or can use an existing USB-A to Lightning cable and a USB-A charger that you might already have.

If purchasing new, the Anker USB-C chargers or the Apple 20W USB-C would be common choices.

If you have the power adapter and the cable from an older iPhone, you can use them.

If you need to purchase a power adapter to work with the cable that comes with the iPhone 13, the following is the one typically used: Buy 20W USB-C Power Adapter - Apple but higher wattage ones can also be used.

And you might also want to look at the Anker Nano series. If you buy from a 3rd party ensure they are Made for iPhone (mfi) certified, Anker is.