Fetch data from two table in a php file

Question

i have online store and i want to make an api for it i have a three tables in MySql database i Should use to fetch the product details file_path for the product image url invetory_details for price tbl_product for the product details like (name , description, digital or physical...etc) i didn't know how to fetch data from more than one table please help me with this. this is my code i was able to fetch data from one table

  define('DB_HOST','localhost');
  define('DB_USER','admin');
  define('DB_PASS','123456');
  define('DB_NAME','testname');
  
  $conn = new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME);
  if (mysqli_connect_errno()){
      die('error'.mysqli_connect_error());
  }
  $stmt = $conn->prepare( "SELECT id, upc_code, category_id, sub_category_id, sub_subcategory_id, name, description, brand_id , digital, license_key_code, active , added_by_id, sort_order, rating, added_at, updated_at FROM tbl_product;");
  $stmt->execute();
  $stmt->bind_result($id, $upc_code, $category_id, $sub_category_id, $sub_subcategory_id, $name, $description, $brand_id, $digital, $license_key_code, $active, $added_by_id, $sort_order, $rating, $added_at, $updated_at);
  $product= array();
  
  while($stmt->fetch()){
      $temp=array();
      $temp['id']=$id;
      $temp['upc_code']=$upc_code;
      $temp['category_id']=$category_id;
      $temp['sub_category_id']=$sub_category_id;
      $temp['sub_subcategory_id']=$sub_subcategory_id;
      $temp['name']=$name;
      $temp['digital']=$digital;
      $temp['active']=$active;
      $temp['added_by_id']=$added_by_id;
      $temp['sort_order']=$sort_order;
      $temp['rating']=$rating;
      $temp['added_at']=$added_at;
      $temp['updated_at']=$updated_at;
      
      array_push($product, $temp);
  }
  echo json_encode($product);