Display posts from #6 to #20 on archive page

Add offset in the query and give value as 5 so, the first 5 will be skipped.

Below is code snippet for the same

$custom_args = array('post_type' => 'your custom post type name',
'posts_per_page' => '20',
'orderby' => 'id',
'offset'=>5,
'order' => 'ASC',);
$custom_query = get_posts($custom_args);
 foreach ($custom_query as $value) {
 //your data
  }