Hello Jannaz,
Please find the codes on theme from cpanel or FTP on wp-content/themes/corporate-plus-pro/acmethemes/sidebar-widgets/acme-service.php and find the codes on line number 213, <p><?php echo esc_html( $sub_title ); ?></p> and remove esc_html and make it <p><?php echo $sub_title; ?></p>. Hope this will help to add the HTML tags on the Service Widget descriptions section. If you need to enable on other widgets, you can find the similar codes on widgets and make like the reference above.
Please try this and let us know about the result.
Warm Regards