If you have the Magic Keyboard you’re all set—output to the monitor via the iPad’s usb port and charge via the other usb port on the keyboard. Otherwise you’ll need a hub or something similar. I just purchased the Anker 7-in-1 and it’s working well so far.
Quick tip: If you go with one of these options but have problems with the display or charging, swap out some different cables and power bricks. I had to use a different brick and a different cable with the Anker hub. iPad and MKB combo was more forgiving. Good luck!