OnTriggerEnter Get Key

try using this code you need to have a tag "house" attached to the house

     using UnityEngine;
     using System.Collections;
 
 public class enteringthehouse : MonoBehaviour {
     
     bool enter; // boolean to determine whether you are inside the trigger or outside
         
     void Start () {
         enter = false; // before entering the trigger area
     }
     
     // Update is called once per frame
     void Update () {
         if (enter == true&& Input.GetKeyDown(KeyCode.Space)) // determine that only after the trigger is
         {                                                    // true and you press space you can enter the house
             Debug.Log ("you can enter the house");//open the door ?/ change to other scene ? up to you
                                                  // just put the code here
         } 
     }
     
     void OnTriggerEnter (Collider collider)
     {
         if (collider.gameObject.CompareTag ("house")) //entering the trigger/collider attached to the
                                                     // house. the house object must have tag named "house" 
         {                                            // with both of these enter will only be true when you are 
             enter = true;                             // inside the trigger
         } 
     }
     
     void OnTriggerExit (Collider collider)
     {
         if (collider.gameObject.CompareTag ("house")) //exiting the trigger/collider attached to the 
         {                                                // house cause enter to become false
             enter = false;                                        
         } 
     }
 }