I am new to Unity and I imported a model made of smaller meshes into unity and gave them textures, however I want to give the model a convex mesh collider but when I do so it starts doing weird things like floating in air or simply rotating with no stop. Is it possible I can give all the meshes a singular mesh collider?
No, as that would require re-generating the collider from scratch every time any of the objects move which would be extremely costly.
But you can have multiple MeshColliders for a single Rigidbody, which accomplishes the exact same thing. Just parent all your MeshColliders under an object that has the Rigidbody component.
On a side note, giving a convex MeshCollider to an object will not cause it to float or rotate non-stop. There’s clearly something else going on.