Yes, the 108W Pro USB-C PD Desktop Charger can charge a 3rd generation iPad Pro. Satechi has confirmed iPad Pro 12.9-inch (3rd generation) with the 108W Pro USB-C PD Desktop Charger.

• Use the 90W USB-C PD port. The 90W USB-C PD port automatically adjusts its output to properly charge your iPad.
• You can also use the second USB-C PD port, which provides up to 18W.

Charging cables are sold separately. For the fastest and safest charge, use the original device cable or a certified cable.