NavigationAI.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.AI;
public class NavigationAI : MonoBehaviour
{
    public GameObject theDestination;

    private NavMeshAgent theAgent; 
    
    public GameObject walkingBoundary;

    private Vector3 agentOrignalPosition;
    
    // Start is called before the first frame update
    void Start()
    {
        theAgent = GetComponent<NavMeshAgent>();
        agentOrignalPosition = theAgent.transform.position;
    }

    // Update is called once per frame
    void Update()
    {
        if (walkingBoundary.GetComponent<MeshCollider>().bounds.Contains(theDestination.transform.position))
        {
            theAgent.SetDestination(theDestination.transform.position);
        }
        else
        {
            theAgent.SetDestination((agentOrignalPosition));
        }
    }
}