How to get the current template name

WordPress uses the get_page_template_slug() function to get the current page template name. This function returns the page template file name. For example, if you have a template like page-xxx.php, this function returns page-xxx.php.

$template_name = get_page_template_slug( get_the_ID() ); 
// $template_name may contain 'page-xxx.php

This function takes a page ID as an argument and returns the slug of the custom template set for that page. If no custom template is set, it returns an empty string.