Add extra fee to COD payment gateway

extra-fee.php

<?php
// =========================================================================
// ADD EXTRA FEE TO SPECIFIC PAYMENT GATEWAY => COD
// =========================================================================
// Part 1: assign fee
function add_checkout_fee_for_gateway() {
    foreach( WC()->cart->get_cart() as $cart_item_key => $cart_item ) {
        // Check if there are non-virtual products
        $chosen_gateway = WC()->session->chosen_payment_method;
        if ( $chosen_gateway == 'cod' ) {
            // Note: edit "Fee" and "5" below to control Label and Fee Amount
            WC()->cart->add_fee( __('Utánvét díja', 'woocommerce'), 150 );
        }
    }
}
add_action( 'woocommerce_cart_calculate_fees', 'add_checkout_fee_for_gateway' );
  
// Part 2: reload checkout on payment gateway change
function refresh_checkout_on_payment_methods_change(){
    ?>
    <script type="text/javascript">
        (function($){
            $( 'form.checkout' ).on( 'change', 'input[name^="payment_method"]', function() {
                $('body').trigger('update_checkout');
            });
        })(jQuery);
    </script>
    <?php
}
add_action( 'woocommerce_review_order_before_payment', 'refresh_checkout_on_payment_methods_change' );