/*preload tff fonts*/

function enqueue_scripts_ttf() {
  wp_enqueue_style('ttf-handle', '/yourlink/filename.ttf', array(), null);
}
add_action('wp_enqueue_scripts', 'enqueue_scripts_ttf');


function style_loader_ttf($html, $handle) {
  if($handle === 'ttf-handle') {
return str_replace("rel='stylesheet'", "rel='preload' as='font' type='font/ttf' crossorigin='anonymous'", $html);
  }
  return $html;
}
add_filter('style_loader_tag', 'style_loader_ttf', 10, 2);

/*code ends */

----------------------------------

/*preload woff */

function enqueue_scripts_woff() {
  wp_enqueue_style('woff-handle', '/yourlink/filename.woff2', array(), null);
}
add_action('wp_enqueue_scripts', 'enqueue_scripts_woff');


function style_loader_woff($html, $handle) {
  if($handle === 'woff-handle') {
return str_replace("rel='stylesheet'", "rel='preload' as='font' type='font/woff2' crossorigin='anonymous'", $html);
  }
  return $html;
}
add_filter('style_loader_tag', 'style_loader_woff', 10, 2);

/*code ends */