I've been trying to find out what this does. I see an old question that asked the same thing from 5 years ago: but nobody was able to answer it, or a least nobody that saw it was: What does com.apple.CoreSimulator.CoreSimulatorService do?
I came across it when I was trying to do a Disk Utility Verify & Repair on High Sierra on my internal Data Drive (not my System drive, that's a separate Disk).
And after various attempts, I got a message saying that this service was preventing it. So I killed it, and was then able to do what I wanted without any obvious adverse affects. No Magic Smoke, no Blue Screen of Death etc etc.
Do I actually NEED to have this service running? Activity Monitor says it's consuming a lot of resources (I did not write it down, but will look next time I reboot if it's gone up again).
If there's a good place to read up on Apple things like this that would be even better: I'd rather learn to fish than have someone hand me a can of opened sardines...:-}
Thanks, Alan