WP_Query: How do I sort on meta value and use LEFT JOIN?

WordPress is also provide more filters to change custom queries.
https://codex.wordpress.org/Custom_Queries

add_filter('posts_join', 'custom_query_join' );
$premium = new WP_Query( $premium_args);
remove_filter('posts_join', 'custom_query_join' ); // remove filter bcz not effect to another query to use after this query.

function custom_query_join( $join ){
  $join .= 'Put here join to table';
  return $join;
}