You should note that while your iPad Pro can be charged with a 30W (or other) compatible Power Adapter, it will not charge appreciably faster than when using the USB-C 20W Power Adapter that was likely supplied with your iPad. When charged with a USB-PD Power Adapter, the maximum iPad charging rate is limited to ~20W. When using a standard USB Power Adapter, operating at 5V, the maximum charging rate is limited to 12W (i.e., 2.4A @5V).
Where the higher-power Power Adapter does provide benefit is when being used with other USB devices via a USB-C hub. A higher-output Power Adapter provides a greater “power budget” - allowing other devices to receive power while maintaining the iPad’s maximum 20W charging rate. For example, a USB multiport hub may typically require 10W power; connected USB devices (external storage, keyboard, mouse etc) also draw additional power from the source. If the connected load exceeds the available supply, the iPad may not charge - or may charge at a substantially slower rate. In extremis, both the iPad and Power Adapter will share the connected load - and the iPad may actually discharge its battery to make-up the shortfall in available power from a connected Power Adapter.
You should note that while Apple devices generally support USB PD, they do not support other charging standards - such as QC (Quick Charge).
I hope this insight proves to be helpful in understanding some of the factors that will impact charging of your iPad.
