Add to checkout total lines an additional line below shipping in WooCommerce

You could use the Fee API that will create in totals line below shipping optionsCode goes in function.php file of your active child theme (or active theme). Tested and works., based on the shipping total x 1.5 (+50%), where you can include your conditional logic, like:

add_action( 'woocommerce_cart_calculate_fees','custom_pack_fee', 10 , 1 );
function custom_pack_fee( $cart ) {
    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    if ( ! is_chekout() )
        return;

    // Add your conditional logic and calculations below

    $percentage     = 1.5; // Percentage (150%)
    $shipping_total = $cart->get_shipping_total();

    if ( $shipping_total > 0 ) {
        $cart->add_fee( __('Include pack', 'woocommerce'), ($shipping_total * $percentage), true );
    }
}

Code goes in function.php file of your active child theme (or active theme). Tested and works.