Edit bool on another script and object.

I have been looking for a specific answer for this question, while I have found some similiar nothing for this specific thing. Or at least nothing similiar enough to work.... or I am not looking for the right question.

ObjectA instantiates ObjectB which has its own script (ScriptB) and has the tag TagB (If needed)

I need to change a bool within ObjectB's script from the script on ObjectA (ScriptA).

I know that I do not have much to go on, or to give you to go on, but I really have no idea where to go with this (Have tried way to many things already).

 public class blockProperties : MonoBehaviour {
 
     public bool timer;
     scriptB ScriptB;
     
     // Use this for initialization
     void Start () {
         
     }
     
     // Update is called once per frame
     void Update () {
         timer += Time.deltaTime;
         
         if (timer >= 5f){
             ScriptB.freezeY = false;
         }
         
         
     }
 }

ObjectB's script

 public class scriptB : MonoBehaviour {
 
     public bool freezeY = true;    
     
     // Use this for initialization
     void Start () {

     }
     
     // Update is called once per frame
     void Update () {
         if (freezeY == false)
         {
             GetComponent<Rigidbody>().constraints &= ~RigidbodyConstraints.FreezePositionY;
             
         }            
     }
 }