Magento – Magento 2.2 Programatically apply coupon code

Duplicate the conditions into the "Apply the rile to cart items matching....".
it clearly states in the title "leave blank for all items".

First you need to inject a few classes in your constructor:

protected $cart;
protected $quoteRepository;

public function __construct(
    ...
    \Magento\Checkout\Model\Cart $cart,
    \Magento\Quote\Api\CartRepositoryInterface $quoteRepository
) {
    ...
    $this->cart= $cart;
    $this->quoteRepository = $quoteRepository;
}

Then in your code you can do: Data.php in helper

public function getCouponCode(){
    $cartQuote = $this->cart->getQuote();
    return $cartQuote->getCouponCode();
}

Here use own create function replace $cartQuote->getCouponCode(); to $cartQuote->getOwnFuction(); And put code in getOwnFuction() for apply custom couponCode

And then i put in my function: Vendor\Shipping\Model\Quote\Address\Rate.php

public function importShippingRate(\Magento\Quote\Model\Quote\Address\RateResult\AbstractResult $rate)
{
   $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
   $helper = $objectManager->create('Vendor\Shipping\Helper\Data');

   $couponCode = $helper->getCouponCode();
   echo 'CouponsCode = '.$couponCode;
}