Is it possible to add a render texture to a gameObject through a script?

What Ive been trying to do is create a camera, a cube, and take what the camera sees and display it on the cube. I would like to do all of this through a single script, where I instantiate a cube and camera prefab, and from there I do the connection between the two.

So far, Ive managed to create both of these objects, and Ive created a render texture, which is assigned to the camera:

GameObject cubo = Instantiate(cuboprefab);
            GameObject camara = Instantiate(prefabCamara);
            cubo.transform.position = new Vector3(0, 0, 0);
            camara.transform.position = new Vector3(0, 0.5f, 3);
            rt = new RenderTexture(256, 256, 16, RenderTextureFormat.ARGB32);
            rt.useDynamicScale = true;
            rt.Create(); 
            var compcam = camara.GetComponent<Camera>();
            compcam.targetTexture = rt;
            //cubo.GetComponent<Renderer>().sharedMaterial = rt;

The last line is commented because thats where my issue is, I cant seem to find a way to assign a RenderTexture object to the material, even though it is something that you can do with the Unity UI.

>Solution :

You are currently trying to assign a material, not the texture of the material. Set the texture to the mainTexture property of the material instead.

cubo.GetComponent<Renderer>().sharedMaterial.mainTexture = rt;