If you have a new 2018 iPad Pro, then you probably need a new USB-C hub. Without it, you can only plug in one accessory at a time, and that includes the charger. With a hub, you can plug in an almost unlimited number of USB devices (and other gear), plus provide power for everything at the same time.
The problem is, almost all USB-C docks are designed for laptop computers like the MacBook. They’re designed with short tails so they can sit on a desk next to the MacBook’s desk-level USB-C port, and plug in without trailing a long cable all over the place. But these short tails are terrible for the iPad — especially if you use the tablet on a stand.
They result in a dongle dangling from the iPad, trailing all the cables and accessories hooked up to the hub. This puts a strain on the USB-C port, and reduces mobility for the iPad. It also looks ridiculous. Ditto those docks that clip to the iPad itself. They’re a disaster waiting to happen. Fortunately, I have a better idea.