preconnect lets the browser start a connection to an external server earlier, reducing load time. Useful for Google Fonts, CDNs, and more. Add to header.php or via wp_head. For more on improving Google Fonts loading with preconnect.
<link rel="preconnect" href="https://fonts.googleapis.com">
<link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>