Success page on payment gateway response magento2

inplement csrf interface in controller

class Success extends \Magento\Framework\App\Action\Action implements CsrfAwareActionInterface
{
protected $_order;
protected $order;
protected $pageFactory;
protected $salesOrder;
protected $checkoutSession;

    public function __construct(Context $context)
    {
        parent::__construct($context);
}



public function createCsrfValidationException(
    RequestInterface $request
): ?InvalidRequestException {
    return null;
}

public function validateForCsrf(RequestInterface $request): ?bool
{
    return true;
}

public function execute()
    {
/**********************/
                     write your code
/**********************/
    } 

}