I have 2 payment method Paypal Express Checkout & Bank Transfer.

When the amount is greater than X then Paypal should not be displayed only Bank Transfer.

I have configured that variable on admin side on `system.xml` for X amount.

By referring to http://magento.stackexchange.com/questions/135302/magento-2-how-do-we-add-zipcode-validation-on-cod-payment-method/135524#135524 as per @Ashish suggestion.

I have below code now

**app\code\Custom\Module\etc\frontend\di.xml**

    <?xml version="1.0"?>
    <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">
    <type name="Magento\Paypal\Model\Express">
            <plugin sortOrder="1" name="restrictByCustomer" type="Custom\Module\Plugin\Payment\Method\Paypal\Available"/>
    </type>

**app\code\Custom\Module\Plugin\Payment\Method\Paypal\Available.php**

    namespace Custom\Module\Plugin\Payment\Method\Paypal;
    
    use Magento\Customer\Model\Session as CustomerSession;
    use Magento\Backend\Model\Auth\Session as BackendSession;
    use Magento\Paypal\Model\Express;
    
    class Available {
    
        /**
         * @var CustomerSession
         */
        protected $customerSession;
    
        /**
         * @var BackendSession
         */
        protected $backendSession;
    
        /**
         * @param CustomerSession $customerSession
         * @param BackendSession $backendSession
         */
        public function __construct(
        CustomerSession $customerSession, BackendSession $backendSession
        ) {
            $this->customerSession = $customerSession;
            $this->backendSession = $backendSession;
        }
    
        /**
         *
         * @param Paypal Express $subject
         * @param $result
         * @return bool
         * @throws \Magento\Framework\Exception\LocalizedException
         */
        public function afterIsAvailable(Express $subject, $result) {
            // Do not remove payment method for admin
    //        if ($this->customerSession->isLoggedIn()) {
    //            return $result;
    //        }
            echo 11;
            exit;
            return true;
        }
    }

So when i access http://localhost/magento2/checkout/cart/#payment, gives Blank page. When i comment lines in `di.xml` then it works fine.