Add a product subtitle to any product.
First, make sure “Product Subtitle” module is enabled in Modules Manager.
In any product’s backend you will find the text-box where to add the subtitle:

To enable the subtitle for the product in Catalog grid, please access Customizer > WooCommerce > Product catalog > Product Components > Product Subtitle and enable it there, plus customize its tag or color eg: https://d.pr/i/4Zq06F .
For the product page, please access Customizer > WooCommerce > Product Page > Components in Summary > Product Subtitle and enable it there eg: https://d.pr/i/te2cql .
Adding shortcodes:
You can add shortcodes if you want to describe a product easier, for example:
Showing Attribute(s)
[rey_attributes id="pa_size" product_id="" limit="3" separator="," link="false"]
This outputs the first 3 size attributes, separated by a comma.
Enable display in Cart & Checkout
You may choose to display the product subtitle in the Cart and Checkout pages by adding the code snippet below into the child theme’s functions.php :
add_filter('reycore/woocommerce/module/product-subtitle/cart_display', '__return_true');