How to add custom product meta or product attributes below the product description?

In order to add (custom) product attributes and product meta below the product description/title, add the below filter to your themes functions.php file.

/**
 * Add product attributes to the product description.
 *
 * @param string                $description Description.
 * @param int                   $item_id     Item ID.
 * @param WC_Order_Item_Product $item        Product.
 *
 * @return string
 */
function add_parent_product_sku( $description, $item_id, $item ) {

    $product = $item->get_product();

    if ( $product ) {

        $description   .= '<br><ul><li><strong>' . esc_html__( 'SKU:', 'woocommerce-pdf-invoices' ) .

            '</strong>' . esc_html( $product->get_sku() ) . '</li></ul>';

    }


    return $description;
}
add_filter( 'wpi_item_description_data', 'add_parent_product_sku', 10, 3, 98 );