Update :3

Assets/Scripts/MeshCombiner.cs

@@ -0,0 +1,67 @@
+using UnityEngine;
+using System.Collections.Generic;
+
+public class MeshCombiner : MonoBehaviour
+{
+    public string tagToCombine;
+    public bool destroyAfterCombine;
+
+    private void Start()
+    {
+        Invoke("CombineMeshes", 0.5f);
+        //CombineMeshes();
+    }
+
+    
+
+    private void CombineMeshes()
+    {
+
+        Debug.Log("started");
+        // Find all game objects with the specified tag
+        GameObject[] taggedObjects = GameObject.FindGameObjectsWithTag("Wall");
+        /*
+        List<GameObject> taggedObjectsList = new List<GameObject>();
+        foreach(GameObject g in upperTaggedObjects)
+        {
+            foreach(MeshFilter mr in g.GetComponents<MeshFilter>())
+            {
+                taggedObjectsList.Add(mr.gameObject);
+                Debug.Log("Added");
+            }
+        }
+        taggedObjectsList.TrimExcess();
+        GameObject[] taggedObjects = taggedObjectsList.ToArray();
+        */
+        Debug.Log(taggedObjects.Length);
+        // Combine all the meshes into a single mesh
+        Mesh combinedMesh = new Mesh();
+        CombineInstance[] combineInstances = new CombineInstance[taggedObjects.Length];
+        for (int i = 0; i < taggedObjects.Length; i++)
+        {
+            combineInstances[i].mesh = taggedObjects[i].GetComponent<MeshFilter>().sharedMesh;
+            combineInstances[i].transform = taggedObjects[i].transform.localToWorldMatrix;
+        }
+        combinedMesh.CombineMeshes(combineInstances, true);
+
+        // Create a new game object to hold the combined mesh
+        GameObject combinedObject = new GameObject(tagToCombine + "_Combined");
+        combinedObject.transform.position = Vector3.zero;
+        combinedObject.transform.rotation = Quaternion.identity;
+
+        // Add a mesh filter and renderer to the combined game object
+        MeshFilter meshFilter = combinedObject.AddComponent<MeshFilter>();
+        MeshRenderer meshRenderer = combinedObject.AddComponent<MeshRenderer>();
+        meshFilter.mesh = combinedMesh;
+        meshRenderer.material = taggedObjects[0].GetComponent<Renderer>().sharedMaterial;
+
+        // Destroy the original game objects if specified
+        if (destroyAfterCombine)
+        {
+            foreach (GameObject obj in taggedObjects)
+            {
+                Destroy(obj);
+            }
+        }
+    }
+}