If you know enough PHP to be dangerous, this tutorial ( with video ) can help you modify the default email templates WooCommerce uses to generate sales emails.
In your WordPress Dashboard, go to WooCommerce > Settings > Emails and click on the Manage button next to the email type you want to modify.
You can then click the copy file to theme button and it will copy the specific template you need to your active theme which should be a child theme of your parent theme.
Make sure you click Save Changes to save the template in your child theme.
In this case, it copied the 1st template in the list for New Orders, admin-new-order.php to this location in the active child theme : 2020-child/woocommerce/emails/admin-new-order.php.
You can then use FTP or cPanel in your hosting account to edit the admin-new-order.php file in your child themes woocommerce/emails folder and modify the default code or add custom code directly to the template.
Any changes you make to the copied file in your child theme will override the same file in WooCommerce however your changes will not be lost when the WooCommerce plugin updates.
Looking for WooCommerce code? Try these code snippets and tutorials.