I’ve been using Fusion 360 for some years now. It is free for hobbyists, parametric, and can output directly to a range of printers (I’ve output directly to Ultimaker printers) and other products such as some CNC routers....
I love Fusion 360 and highly recommend trying it. As mentioned it is free for hobbyists, and lots of YouTube videos on using it. I started with this one and it covers lots of important points ( I still go back to it at times)....
Fusion 360 is going to take some time to get results out of but the sky is the limit pretty much what you can do with it. I'm probably not even using 10% of its features.
Printers are cheap enough now that I'd recommend thinking about getting both types eventually (FDM and resin) I started with an Ender 3 Pro and love it. Use it in the living area with no smell. Parts come out ready to paint. No cleanup. Great for developing an object as you can go from design to print (I have a USB cable between it and computer) in seconds and redesign and print over and over again with no cleanup required. Sure it isn't going to do detail down under 3-4" scale inches in N Scale but ....
... you can't hardly see that detail unless you are viewing within 8-12 inches of a N scale object. You can print larger objects with it...
... like the turntable above and....
.... say the roundhouse you wanted. They would need a more expensive resin printer to fit the print on the build table.
Now saying that for really fine detail like you would want on say a loco you can't beat a resin printer as long as it is large enough to print the object. So for another couple hundred I now also own an AnyCubic Mono for detail work but the Ender 3 Pro will still be the go-to printer for most of my printing,
Sumner