How to Use Object Pooling for a 3D Game?

So, for my project which is a Subway Surfers type game, I'm Instantiating when its clear I should be Pooling. My character moves along the Z Axis and I instantiate and then delete roughly 12 Obstacles every 5 seconds. My Draw Call is at a consistent 250 while my tris is at 144k.

How do I make a pooling system similar to my current system? Heres my current script. If possible, I want to make each tile seamlessly connect.

  using System.Collections;
  using UnityEngine;
  using System.Collections.Generic;
  
  public class TileManager : MonoBehaviour
  {
      public GameObject[] tilePrefabs;
  
      private Transform playerTransform;
      private float spawnZ = -10f;
      private float tileLength = 27.7016f;
      private float safeZone = 22.5f;
      private int amnTilesOnScreen = 4;
      private int lastPrefabIndex = 0;
  
      private List<GameObject> activeTiles;
  
      // Start is called before the first frame update
      private void Start() {
          activeTiles = new List<GameObject>();
          playerTransform = GameObject.FindGameObjectWithTag("Player").transform;
  
          for (int i = 0; i < amnTilesOnScreen; i++)
          {
              if (i < 2)
                  SpawnTile(0);
              else
                  SpawnTile();
          }
      }
  
      // Update is called once per frame
      private void Update() {
          if (playerTransform.position.z - safeZone > (spawnZ - amnTilesOnScreen * tileLength))
          {
              SpawnTile ();
              DeleteTile ();
          }
      }
  
      private void SpawnTile(int prefabIndex = -1)
          {
          GameObject go;
          if (prefabIndex == -1)
              go = Instantiate(tilePrefabs[RandomPrefabIndex()]) as GameObject;
          else
              go = Instantiate(tilePrefabs[prefabIndex]) as GameObject;
          go.transform.SetParent(transform);
          go.transform.position = Vector3.forward * spawnZ;
          spawnZ += tileLength;
          activeTiles.Add (go);
      }
  
      private void DeleteTile()
      {
          Destroy(activeTiles[0]);
          activeTiles.RemoveAt(0);
      }
  
      private int RandomPrefabIndex()
      {
          if (tilePrefabs.Length <= 1)
              return 0;
  
          int randomIndex = lastPrefabIndex;
          while (randomIndex == lastPrefabIndex)
          {
              randomIndex = Random.Range(0, tilePrefabs.Length);
          }
  
          lastPrefabIndex = randomIndex;
          return randomIndex;
      }
  
  }