You can change the contents of all emails by overriding the templates from your (child) theme. Read the documentation on Template Structure for more information on where all the files are located and how you can override them.
For example, say you would like to override the admin order notification, copy: the templates/emails/admin-new-order.php file from the WooCommerce plugin to woocommerce/emails/admin-new-order.php in your (child) theme and you can customise it there. This way it will upgrade safe, so the changes are not lost when updating the plugin.