How can I adjust the styling of the line added to WooCommerce emails?

To do this, apply CSS styling. The paragraph has CSS ID openinghours_adminlabel, and the chosen time has CSS ID openinghours_email_timechosen.

One way to do this is by adding a CSS rule via a code filter. e.g.:

add_action('woocommerce_email_header', function ($email_heading, $email) {
// Adds CSS to "new order" email only
if ($email->id != 'new_order') return;
<style type="text/css">
p#openinghours_adminlabel { font-size: 28px; }
}, 20, 2);

Posted in: WooCommerce Opening Hours and Delivery Times