Hi David,
Congratulations on your newly purchase Surface device.
Yes, the Surface Pro 9 is compatible with a monitor. It has a USB-C port that supports video output, so you can connect it to a monitor that has a USB-C port or use an adapter to connect it to a monitor with HDMI or DisplayPort. You can also use the Surface Dock to connect to multiple monitors and other peripherals. It supports up to 2 external monitors. You can find more details from this troubleshooting article, Troubleshoot connecting Surface to an external display - Microsoft Support.
It is worth noting that the Surface Pro 9 has been tested with various external monitors, docks, cables, and adapters by Surface engineering to ensure the best experience.
I hope these answers your question.
Kind regards,
Lavenia