It seems you’re looking for the tag
parameters:
$args = array(
'posts_per_page' => 5,
'tag' => 'YOUR-TAG-SLUG',
'orderby' => 'date',
'order' => 'DESC',
);
$query = new WP_Query($args);
while ($query->have_posts()) :
$query->the_post();
...
endwhile;
// don't forget to reset/restore the query
wp_reset_postdata();