Display Modified date in RSS feed in wodfpress

I created wordpress dashboard widget to show feed from another site I run.I would like to order it by modified date as appose to published date.As I can imagine this might not be possible, can i at least then display the modified date?Thank you

function dashboard_custom_feed_changelog() {    $feeds = array(        array('url' => 'https://website.com/tag/changelog/feed/','title' => 'Feed Title','items' => 20,'show_summary' => 1,'show_author' => 0,'show_date' => 1,'orderby' => 'post_modified'     ));        ob_start();     wp_dashboard_primary_output( 'dw_dashboard_widget_onion', $feeds );    $buffer = ob_get_clean();     $result = str_replace("<a class='rsswidget'","<a class='rsswidget' target='_blank'", $buffer);    echo $result;}add_action('wp_dashboard_setup', 'wpc_dashboard_widgets'); ````