Connect iPad Pro 2 to iMac using USB C to Thunderbolt

An iPad Pro 2nd Generation has neither a Thunderbolt nor a USB-C port.

The iPad Pro 2 has a Lightning Port.

If your iMac has USB-C ports, you can use a USB-C to Lightning cable, to connect it, and charge it yes.

If your iMac has Thunderbolt ports, then you would need a Thunderbolt to regular USB (not USB-C).

If it has a USB-C port, the you do NOT have an iPad Pro 2, but the newest 2018, iPad Pro 3?

Does your iPad Pro have a Home button, or not?

Maybe, but not 100% sure that will work.

Look in the questions and answers section for the adapter here: Questions about Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter - Apple

If the iPad has a USB-C port, then its an iPad Pro 3rd Generation.

You can then use a Thunderbolt 2 to USB adapter, and a USB to USB-C cable. Don't believe there's a Thunderbolt 1/2 to USB-C adapter.

That's a mini DisplayPort cable. It is not full Thunderbolt and as such would only try to transfer a video signal, and not data or power.

You'll need an actual Thunderbolt 2 adapter or a Thunderbolt dock with USB ports, for data and power required by the Duet app.