Wordpress sub-categories of parent category from the current post

wordpress.post.php

<?php 
	# https://wordpress.org/support/topic/how-to-only-show-the-posts-child-category-inside-the-loop

	$post_child_cat = array();
	
	foreach( (get_the_category()) as $cats) {
		$args = array( 'child_of' => $cats->cat_ID );
		$categories = get_categories( $args );
		if( $categories ) foreach( $categories as $category ) echo '<li><a href="/cat='. $category->cat_ID.'">' . $category->cat_name . '</a></li>';
	} 
?>