Is there anyway to batch renaming via Editor [not on Runtime] multiple game objects in the hierarchy ?

Yes, it’s possible using a custom editor window. Like this:

 using UnityEngine;
 using UnityEditor;
 
 public class RenameChildren : EditorWindow {
     private static readonly Vector2Int size = new Vector2Int(250, 100);
     private string childrenPrefix;
     private int startIndex;
     [MenuItem("GameObject/Rename children")] public static void ShowWindow() {
         EditorWindow window = GetWindow<RenameChildren>();
         window.minSize = size;
         window.maxSize = size;
     }
     private void OnGUI() {
         childrenPrefix = EditorGUILayout.TextField("Children prefix", childrenPrefix);
         startIndex = EditorGUILayout.IntField("Start index", startIndex);
         if (GUILayout.Button("Rename children")) {
             GameObject[] selectedObjects = Selection.gameObjects;
             for (int objectI = 0; objectI < selectedObjects.Length; objectI++) {
                 Transform selectedObjectT = selectedObjects[objectI].transform;
                 for (int childI = 0, i = startIndex; childI < selectedObjectT.childCount; childI++) selectedObjectT.GetChild(childI).name = $"{childrenPrefix}{i++}";
             }
         }
     }
 }

To use it:

1. Save the script in your project.

2. Go to GameObject/Rename children.

3. Select the parent of the objects to rename.

4. Fill the fields and press the button.

Thanks @RaptorRush this works perfectly and exactly what i was looking for :)

I couldn't do it can you help me it gives an error

I thought I would add a way to rename selected objects in case you are not naming the child objects.

 using UnityEditor;
 using UnityEngine;
  
 public class RenameSelected : EditorWindow
 {
     // public fields
     public GameObject[] objects;
     
     // private fields
     private static readonly Vector2Int size = new Vector2Int(250, 100);
     private string _gameObjectPrefix;
     private int _startIndex;
     private SerializedObject _serializedObject;
  
     [MenuItem("GameObject/Rename Selected")]
     public static void ShowWindow()
     {
         EditorWindow window = GetWindow<RenameSelected>();
         window.minSize = size;
         window.maxSize = size;
     }
  
     private void OnEnable()
     {
         ScriptableObject target = this;
         _serializedObject = new SerializedObject(target);
     }
  
     private void OnGUI()
     {
         _gameObjectPrefix = EditorGUILayout.TextField("Selected Prefix", _gameObjectPrefix);
         _startIndex = EditorGUILayout.IntField("Start Index", _startIndex);
         
         _serializedObject.Update();
  
         SerializedProperty serializedProperty = _serializedObject.FindProperty("objects");
  
         EditorGUILayout.PropertyField(serializedProperty, true);
  
         if (GUILayout.Button("Rename Objects"))
         {
             
             for (int objectI = 0, i = _startIndex; objectI < serializedProperty.arraySize; objectI++)
             {
                 serializedProperty.GetArrayElementAtIndex(objectI).objectReferenceValue.name = $"{_gameObjectPrefix}{i++}";
             }
         }
         
         _serializedObject.ApplyModifiedProperties();
     }
 }

This will create an array, in the editor window, simply select the order of the GameObjects, then set your prefix and start index, and hit the Rename Objects button.

-Larry