Loop Custom Post Type Sub Category

<?php
wp_reset_postdata();
  
$args = array(
           'post_type'      => 'posttype',
           'posts_per_page' => 20,
           'tax_query' => array(
               array(
                   'taxonomy' => 'taxonomy',
                   'field'    => 'slug',
                   'terms'    => 'subcategory',
               ),
           ),
       );                  

$query = new WP_Query( $args ); ?>
 
<?php if ($query->have_posts()) : while ($query->have_posts()) : $query->the_post(); ?>
 
 
 
<?php endwhile; endif; ?>
 
<?php wp_reset_postdata(); ?>