Hi @PickyInspector & welcome to the forums 
VATSIM (short for the Virtual Air Traffic Simulation Network) is a completely free online platform which allows virtual pilots, wherever they are in the world, to connect their flight simulators into one shared virtual world. VATSIM also simulates air traffic control in this virtual world, creating the ultimate as-real-as-it-gets experience for you, the virtual aviation enthusiast.
However, it appears it is not compatible with XBox:
https://forums.flightsimulator.com/t/vatsim-integration-msfs-2024-wish-list/646896/2?u=smotheryvase665
If it turns out that is is compatible with Xbox, this group is looking for more users to join them:
Hope this helps! 