WP_Panda

$tax = 'pa_заданный_вами_слаг_атрибута'
$pa_args = get_terms( $tax, array(
			'hide_empty' => false,
		)
 );

$pa_args = array();
    $attribute_taxonomies = wc_get_attribute_taxonomies();
    if ( 0 !== count( $attribute_taxonomies ) ) {
        foreach ( $attribute_taxonomies as $one_tax ) {
            $pa_args[] = get_terms( $one_tax, array(
                    'hide_empty' => false,
                ) );
        }
    }

$test_query_args = array(
    'post_type' => 'question', 
    'posts_per_page' => 4, 
  );

$end_variable = array();
  $test_json_query = get_posts( $test_query_args );
  
  foreach ( $test_json_query as $post ) : 
    	setup_postdata( $post );

    	$end_variable[] = get_the_title();
  endforeach;
  wp_reset_postdata(); 

  return rest_ensure_response( $end_variable );