In any event the 12W USB power adapter that comes with the Apple 10.5-inch iPad Pro is out of reach, you can always use an alternative charger like the Anker PowerPort+ 5 USB-C with the iPad. Let's see how well this Anker portable charger supplies power to the 10.5-inch iPad Pro using USB Power Delivery when connected over the Apple USB-C to Lightning Cable.
The Anker PowerPort+ 5 USB-C promotes 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), 30 watts (15 volts @ 2 amps), and 35 watts (20 volts @ 1.5 amps) power output through its rear USB Type-C port. When observed through the GRL-USB-PD-A1 app by Granite River Labs, Anker instead repeatedly offers 15 watts (5 volts @ 3 amps), 27 watts (9 volts @ 3 amps), and 45 watts (15 volts @ 3 amps) to the 10.5-inch iPad Pro over USB Power Delivery. This is potentially dangerous given the charger is only rated to up to 30 watts, as it may cause the AC adapter to eventually overheat.
Starting from a 2% battery charge, we can see the 10.5-inch iPad Pro first requests 15 watts (5 volts @ 3 amps) from the Anker charger which it then accepts.
After responding to a Discover Identity request by Anker, the 10.5-inch iPad Pro follows up to request the max 45 watts (15 volts @ 3 amps) charging power which is then accepted by Anker.
When first plugged in at 2% battery and turned on, the 10.5-inch iPad Pro initially pulls around 2.6 amps current at 5 volts from the Anker charger in the first 10 seconds. After requesting 45 watts (15 volts @ 3 amps) from the negotiation, the iPad can be seen charging at about 32.1 watts (15.3 volts @ 2.1 amps).
It's good to see that the 10.5-inch iPad Pro can extend beyond the Apple platform to support charging with certain non Apple based chargers like the third party Anker PowerPort+ 5 USB-C. The higher power supplied by Anker also allows the iPad to charge at a much faster rate than using its own 12 watts based charger.
However do take caution when using this charger with any notebook PC that tries to draw more than 30 watts. With Anker actually displaying in the above power delivery protocol transactions that it can supply 45 watts rather than the 30 watts that it's rated for, there's a high chance the AC adapter may overheat when providing 45 watts resulting in a potentially hazardous situation.