Apple products that implement AAC over A2DP only do so on iOS devices (and in only limited cases), and also do not implement anything else (such as any form of AptX, or LDAC).
you can tell macOS to use AAC using an Apple tool called "Bluetooth Explorer". Also, Macs equipped with a T2 chip default to using AAC even without the manual intervention.
You can check what codec is used by alt-clicking the bluetooth icon in your menu bar and hovering over your headphones. There will a an "Active Codec" entry that shows which one is used (during playback).
Apple products that implement AAC over A2DP only do so on iOS devices (and in only limited cases), and also do not implement anything else (such as any form of AptX, or LDAC).