How can I extend the search in WordPress to include custom post types? (Guide, 2023)

/**
 * This function extends the default WordPress WP_Query object 
 * to include an array of post types instead of the default 'post'
 * post type.
 */
function add_post_types_to_search_query(WP_Query $query): void{
  // Skip if this call has been triggered for an administrative interface page.
  if(is_admin()){
    return;
  }
  
  // Skip this call if this is not the search query and if this is not the main query.
  if(!$query->is_search() || !$query->is_main_query()){
    return;
  }
  
  // Define which post types should be searched
  $list_of_post_types = ['post', 'pages'];
  
  // Now - if we get to this point, this must be the search query which we will modify.
  $query->set('post_type', $list_of_post_types);
}
add_action('pre_get_posts', 'add_post_types_to_search_query', 10, 1);

/**
 * This function extends the default WordPress WP_Query object 
 * to include an array of post types instead of the default 'post'
 * post type.
 */
function add_post_types_to_search_query($query){
  // Skip if this call has been triggered for an administrative interface page.
  if(is_admin()){
    return;
  }
  
  // Skip this call if this is not the search query and if this is not the main query.
  if(!$query->is_search() || !$query->is_main_query()){
    return;
  }
  
  // Define which post types should be searched. Replace/Extend by your post types.
  $list_of_post_types = array('post', 'pages');
  
  // Now - if we get to this point, this must be the search query which we will modify.
  $query->set('post_type', $list_of_post_types);
  
}
add_action('pre_get_posts', 'add_post_types_to_search_query', 10, 1);

namespace My_Search{
  /**
   * This class extends the default WordPress WP_Query object
   * to include an array of post types instead of the default 'post'
   * post type.
   */
  class Search_Query_Post_Type_Modifier{
    /**
     * There should never be more than one object of this class therefore
     * we need to create a Singleton
     */
    private static ?Search_Query_Post_Type_Modifier $_instance = null;
    
    /**
     * This function will allow us to access the instance of this class
     */
    public static function get_instance(): Search_Query_Post_Type_Modifier{
        if(null === self::$_instance){
           self::$_instance = new Search_Query_Post_Type_Modifier();
        }
      
      	return self::$_instance;
    }
    
    /**
     * Private constructor to disable multiple instances of this object.
     */
    private function __construct(){
     	add_action('pre_get_posts', [$this, 'add_post_types_to_query']);
    }
    
    /**
     * Add the post types to the search query
     */
    public function add_post_types_to_query(WP_Query $query): void{
  		// Skip if this call has been triggered for an administrative interface page.
  		if(is_admin()){
           	return;
        }

        // Skip this call if this is not the search query and if this is not the main query.
        if(!$query->is_search() || !$query->is_main_query()){
          	return;
        }

        // Define which post types should be searched
        $list_of_post_types = ['post', 'pages'];

        // Now - if we get to this point, this must be the search query which we will modify.
        $query->set('post_type', $list_of_post_types);
  	}
  }
  
  /**
   * Instantiate the object
   */
  Search_Query_Post_Type_Modifier::get_instance();
}

add_action('pre_get_posts', function(WP_Query $query){
   if(!is_admin() && $query->is_search() && $query->is_main_query()){
     $query->set('post_type', ['post','page']);
   }
}, 10, 1);