How do I buy an adapter

https://www.apple.com/shop/product/MD837AM/A/apple-world-travel-adapter-kit

compatibility with MacBook chargers (not iPhone chargers).

NO transformers required for any recent Apple equipment. All adapt automatically. Now its down to the local plugs.

MacBook Pro charger's compact local plug is removable -- it slides to the side and comes right off. You are more likely to find the "extension cord" variant at your local Apple store.

as for the iPhone and iPad chargers -- their adapters would cost more than a new charger. Maybe you could find a cheap adapter locally. Charge with a lightning cord from your MacBook Pro as a work-around, then buy a new charger.

Apple also used to sell an international adapter set in the Apple store -- half a dozen plug adapters for all over the world.

Go to an electronics store or order one online. What seems to be the issue?

https://www.google.com/search?client=firefox-b-1-d&q=us+to+nz+plug+adapter