Using my iPad Pro as a secondary display to a monitor

I just received my iPad Pro and I bought a HDMI to USB-C adapter. I want to connect my iPad Pro to my Dell Monitor and use them as 2 separate screens.

Currently, when I connect my iPad to the monitor with the adapter, the display on the Dell monitor mirrors the iPad screen and adapts to the same screen size as the iPad. Ideally it would fill the whole screen.