The Apple 30W USB-C Power Adapter is almost similar to Apple's first USB Type-C Power Adapter, the 29W USB-C Power Adapter, which you can use to charge your Apple MacBook (Early 2016), Apple MacBook (Early 2015) or Apple's 11-inch iPad Pro (2018) at 15-20 volts.
The Apple 30W USB-C Power Adapter uses USB Power Delivery technology to support fixed PDO's of 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), 30 watts (15 volts @ 2 amps) and 30 watts (20 volts @ 1.5 amps) for output charging.