Conditional check if page is parent or child in WordPress

If you need to display something only if post has childs (or not), you can use this conditional in your code.

<?php


$args = array(
    'post_parent' => get_the_ID(), // Current post's ID
);
$children = get_children( $args );
// Check if the post has any child
if ( ! empty($children) ) {
    // The post has at least one child
  echo "has childs";
} else {
    // There is no child for this post
    echo "do not have childs";
}

?>