pewc_filter_group_title.php

<?php
/**
 * Filter heading tag for group headings
 */
function prefix_filter_group_title( $title, $group, $group_id ) {
    $group_title = pewc_get_group_title( $group_id, $group, true );
    return sprintf( '<h3>%s</h3>', esc_html( $group_title ) ); // Change your tags here
}
add_filter( 'pewc_filter_group_title', 'prefix_filter_group_title', 10, 3 );