You can run RF with an emulator I think.
You can, but it runs HORRIBLY. I've tried, and gave up on RF. If you really want to run RealFlight, you need to do a BootCamp setup, where you have a PC partition to run it.
If you want, AeroFly RC 7/8 will run on a Mac. I'm currently running 7 on my 2014 Mac Mini, and it runs ok. If I run it on my dad's 2018 iMac, it runs much smoother, with graphics turned up to full, and it'll run on Catalina. But, it's $129 for ver. 8 - you get a bunch of field locations and different planes. You can buy 7 through the app store for like, $40, I think? Only downside is it's limited to a couple dozen planes and 4 fields, whereas the full blown version for $130 gives you something like 200 models to fly with and 10-15 locations to fly at. I've been tempted to buy it, but it's a little more than I want to spend at the moment.
If you want a quadcopter sim, Liftoff is the best one I've found for Mac. Others will probably suggest DRL or FPV Freeride, but I've not found them to be as true for simulation as Liftoff, IMHO. Liftoff is something like $20 through Steam, if I remember correctly...