How can i change the walls height and keep the size for example 100x100 but height 0.1 ?

This is the original code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class WallsTest : MonoBehaviour
 {
     // using a GameObject rather than a transform
     public GameObject prefab;
     public float wallsSize;
     public Vector3 wallsStartPosition;
 
     // list updated to GameObject
     private List<GameObject> walls = new List<GameObject>();
 
     void Start()
     {
         for (int i = -2; i < 2; i++)
         {
             // instantiate GameObjects
             GameObject go = Instantiate(prefab);
             go.transform.parent = transform;
 
             // defaults
             Vector3 scale = new Vector3(wallsSize, wallsSize, wallsSize);
             Vector3 adjustedPosition = wallsStartPosition;
 
             // change y position of wall
             adjustedPosition.y += wallsSize / 2;
 
             // use i sign as switch
             float sign = Mathf.Sign(i);
             if ((i * sign) % 2 == 0)
             {
                 // change x position and thickness of wall
                 adjustedPosition.x += wallsSize * sign;
                 scale.z *= 2;
                 scale.x = 0;
             }
             else
             {
                 // change z position and thickness of wall
                 adjustedPosition.z += wallsSize * sign;
                 scale.x *= 2;
                 scale.z = 0;
             }
 
             // set scale and position of wall
             go.transform.localScale = scale;
             go.transform.localPosition = adjustedPosition;
 
             // add wall. do you even need this?
             walls.Add(go);
         }
     }
 }

What i'm getting as result is this: The rectangle of the walls is 100x100 and the scale on Y is also 100 the height of the walls is 100

But i want to have a public variable type float so i can change the height of the walls but keep the size. For example to this. I changed it manual after running in the scene but i want to be able to change the height of the walls before running by changing public float: So it will keep the size 100x100 but the scale on Y the height will be 0.1 or any other value 0.1 or 0.6 or 100 or 30.