Get children of taxonomies

not actually sure what you are trying to achieve with the code. I would write something like this to get the child terms

 $terms = get_terms([
        'taxonomy' => array('Movies, Musics, Books, Games'),
        'parent' => 0,
        'hide_empty' => false,
 ]);

if ( ! empty( $terms ) && ! is_wp_error( $terms ) ) {

    foreach ($terms as $term) {

        $child_term =  get_term_children( $term->term_id, $term->taxonomy )

         //your code here
    }

}