How to realize the gameobject suddently become a cube just because my string equals to "Cube"

Data is getting from the server. The data contains the object's name and position, then it transforms into a corresponding position in the scene. For example, I get message from json：{"Name":"orange" "Position":"x = 1, y=2"}. I am a beginner at Unity. I am engaged in UI design, and my basic knowledge of code is relatively weak. Please forgive me if it is clearly stated.Thanks a lot !!! using System; using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI;

 public class SpawnCube : MonoBehaviour
 {
     public GameObject orange;
     public Transform spawnPosition;
     public string output;
      
     Vector3 spawnPoint;
     void Start()
     {    
     }
     void Update()
     {
         spawnPoint = spawnPosition.position;
         string a = GameObject.Find("UIbox2.0/Canvas").GetComponent<GetMQTT>().name;
         string b = "orange";
         if (String.Equals(string a , string b))
         {
             NewOrange();
         }
  
     }
  
     public void NewOrange()
     {
         Instantiate(orange, new Vector3(spawnPosition.position.x + 2f, spawnPosition.position.y - 2f, spawnPosition.position.z), Quaternion.identity);
     }
  
 }