Hi karthikskr,
thakn’s a lot!
I probaly not well explained the problem but I solved this way:
I found this link https://www.wpbeginner.com/wp-themes/how-to-display-only-child-category-in-your-wordpress-post-loop/
the code is
<?php
foreach((get_the_category()) as $childcat) {
if (cat_is_ancestor_of(10, $childcat)) {
echo '<a href="'.get_category_link($childcat->cat_ID).'">';
echo $childcat->cat_name . '</a>';
}}
?>
