I need to create the unctionality in such a way that whenever customer click on unsubscription link, that information updates the ( "No Longer Contact by email" OOB field) in the database.
Could anyone give me some suggestion/solution to approach this.
Did you see this section of the documentation, explaining how to manage subscriptions and unsubscriptions? https://docs.campaign.adobe.com/doc/AC6.1/en/WEB_Web_Forms_Creating_a_Web_form.html#Subscr iptions
for standard: Adobe Campaign Help | Creating a service
Create your unsubscribe landing page and Publish it.
On the landing page's dashboard, you will get the URL associated with it.
Create a new personalization block and define this unsubscribe link inside it.
On the delivery template or a new created delivery, add this personalization block and now every new email originating from that template will have this link added to it.