Does iPhone 16 Pro Max use USB-C for Charging?

the A1719 usb-c power adapter I have is from my old MacBook pro and says 87w on it, so I was wondering if it is safe to use on the iPhone 16 pro max?

Absolutely. Note though that the phone won't charge any faster with the 87w power adapter than it will with a 27-28w adapter.

Most users are not aware that the "charger" is actually in the phone and it automatically controls the amount of current flowing to the battery.

Yes. You can use any power adapter, though it's strongly recommended that you use only Apple adapters or third-party adapters that are certified to work with Apple devices. Cheap third-party power adapters have been known to frequently damage the device they're connected to.

Regards.

Again, yes, it is. The iPhone will control the amount of power it receives.

Regards.