Can I use my MacBook Pro 87W USB-C Power Adapter to charge my iPhone 12 pro Max safely?

Yes.

Fast charge your iPhone

Use fast charge with certain iPhone models. You can recharge your iPhone to 50 per cent battery in around 30 minutes.

You can fast charge your iPhone 8 and later to 50 per cent battery in around 30 minutes.1

Fast charging works when you use an Apple USB-C to Lightning cable and one of these adapters:

• Apple 18W, 20W*, 29W, 30W, 61W, 87W or 96W USB-C Power Adapter
• A comparable third-party USB-C power adapter that supports USB Power Delivery (USB-PD)

If you're not sure which Apple Power Adapter you have, check the wattage on the top or bottom of the adapter:

*You will need a 20W or higher power adapter to fast charge your iPhone 12.