As 3dm(Rhino 3D models File extensions) is not a real “standard” model exchange format - many programs can’t open it
- won’t find many repositories of models in Rhino format. One of the places I do know is the

https://flyingarchitecture.com/store
https://parametric-architecture.com/10-website-for-free-rhino-3d-models/?srsltid=AfmBOoqCFszSEgEVJP14XK6A5XcOMt6_IVLO0iBeBiS2HT8cmp5jJpxJ
https://www.reddit.com/r/rhino/comments/7z7cip/where_can_i_find_free_rhino_3dm_tree_models/
https://www.reddit.com/r/rhino/comments/x0sbaf/i_created_a_free_catalog_of_architectural_models/
https://www.reddit.com/r/rhino/comments/1y010t/are_there_any_furniture_libraries_out_there/
site, they have lots of great Rhino-format models they share for free (you do have to sign up).

tutorial(Cautions for use are included. Importing a Rhino Model to 3dsMax and setting Up a render in Corona Renderer) :

https://www.youtube.com/watch?v=9OJ2hbfBgpw
https://www.youtube.com/watch?v=l_T5t9luiRg https://www.reddit.com/r/rhino/comments/1g9jlyf/does_rhino_have_a_place_to_download_free_models/
https://discourse.mcneel.com/t/model-resources/26934/3