The Auth0 login form is called Lock and it's <a href="https://github.com/auth0/lock">open source on GitHub</a>. You can style the form like any of your site components by enqueuing a stylesheet in your theme. Use the <a href="https://developer.wordpress.org/reference/hooks/login_enqueue_scripts/"><code>login_enqueue_scripts</code></a> hook to style the form on wp-login.php, <a href="https://developer.wordpress.org/reference/hooks/wp_enqueue_scripts/"><code>wp_enqueue_scripts</code></a> to style widgets and shortcodes, or both to affect the form in all locations.