Msfs ATC is terrible in this respect,
It does not vector you for nearby traffic so if you are flying a PMDG 737 for example with AIG at say 90% you will see lots of aircraft on screen and I have many traffic advisories and resolution advisories on a lot of flights as all ATC tell you whether traffic is in sight or not
It’s totally unrealistic as this would be exceedingly rare IRL
The times my TCAS goes off is ridiculous but it’s just another element of a not very good ATC in msfs
And yes , you can see the aircraft if you ignore TCAS even the planes liveries as they zoom past you so close or even straight at you if you don’t intervene manually on the resolution advisory