You can verify the customer is subscribed or not by the customer email id or Customer Id from the Newsletter Module.
Use Factory,
Magento\Newsletter\Model\SubscriberFactory
With isSubscribed() method you can check the Specific Customer is Subscriber to the newsletter.
Hello buddy i am struggling from couple of day . can you please help me. Magento 2.3.x: Allows customers to choose dropdown option to tax prices including or excluding on product page
https://magento.stackexchange.com/questions/302622/magento-2-3-x-allows-customers-to-choose-dropdown-option-to-tax-prices-includin