How to generate colliders on a specific model?

I know that there is a way to generate colliders on a prefab, but I have yet to discover if there is a way to do that on a specific instance. Basically, I got this bed model that doesn’t have a prefab tied to it, for it was literally ripped straight out of a folder off my computer and directly into the scene, but I still want to give it collisions. I know that I need to access the object’s import settings, but the only way that I know of is if I click on the prefab in my assets folder, but as previously stated, I don’t have a prefab for it. What should I do?

Try if AddCOmponent > MeshCollider works, if not I cant help you