Change widget titles HTML markup in Genesis Framework. Source: https://sridharkatakam.com/how-to-change-widget-titles-markup-in-genesis/

change-widget-titles-markup.php

<?php

//* Replace <h3> with <h4> HTML tags for all widget titles in Genesis
add_filter('genesis_register_sidebar_defaults', 'prefix_register_sidebar_defaults');
function prefix_register_sidebar_defaults($defaults) {
    $defaults['before_title'] = '<h4 class="widget-title widgettitle">';
    $defaults['after_title'] = '</h4>';
    return $defaults;
}