ipad pro 2020 maximumm watts

PD-compliant chargers will supply a maximum of 18W to iPad models that support fast-charging.

The 30W charger is perfectly safe - and compatible with - your 2020 iPad Pro, but the 30W charger will not charge your iPad any faster than an 18W charger.

Can I be any clearer?

Your iPad Pro will fast-charge at maximum rate when connected to a PD (Power Delivery) compliant charger rated at18W or higher.

Chargers rated above 18W, such as Apple’s 30W charger, are supported - as output Voltage and Current are automatically adjusted to match the maximum charging rate supported by the connected PD-compliant device. That said, higher wattage PD chargers will not charge your iPad any quicker than the 18W specification of the iPad.

It should be noted that the competing “QC” (Quick Charge) standard is not supported by Apple products. Connection of QC chargers, if they work at all, will fall-back to charging at maximum rate determined by the USB standard - 5V/12W.

I hope this information and clarification proves to be helpful to you.