club is fine for clubs (traditionally common in some regions), but it is not a generic tag for miniature railways installations. There are also commercial model railways that are not organized as clubs, but are open to the public (for a fee or for free), either as a standalone attraction, e.g. https://www.miniatur-wunderland.com/
or inside a museum e.g. a small one here https://www.boxenstop-tuebingen.de/
I propose to add the length of rails as a property (the latter has 104m of rail, the former, world‘s largest according to their site, has 15400m of tracks.
I think leisure=miniature_railwaymodel_railway could eventually be a good fit for these although use is still a bit limited
leisure=miniature_railway | Tags | OpenStreetMap Taginfo
There are also vending machines that sell the service of running a model train for a minute or so, inside a glass box: