So I can Google or look up the ads?
Not to sound like a smart a** , try reading your first post on this subject, or try overheard railway systems.
As dwbeckett suggested, “elevated railway systems” or try “suspended railway systems.” You could also go to a hobby shop and see if they offer them.
Frankly, I would just pick up a current issue of “Garden Railways” magazine and browse through the ads. Most of the commercially made systems are advertised there. My brother-in-law has such a system in his basement exercise room down in Charlotte, NC, but I don’t recall the brand name.
My own preference would be for an around-the-wall layout at a lower level, but that would involve a lift-up or drop-down section for access to the room. Still, that’s what I plan to do with my Marklin MAXI stuff if/when I have the space to do it. I have a lot of Farge Scale stuff that will eventually see use outdoors on a garden pike, but I’ll keep the MAXI trains indoors, on a layout adorned with Standard Gauge (tinplate/metal) accessories. The two go surprisingly well together.