By default Netcore email API adds an unsubscribe link at the footer of each email. Hence, below are the couple of elements that you can customize to maintain your branding throughout the unsubscribe process:

Unsubscribe text in the email footer
Brand Logo on the unsubscribe page
You can define the final unsubscribe landing page URL on which we would redirect the users.
You can define the landing page the user gets redirected to by clicking the unsubscribe button.

Unsubscribe link is one of the best practices to maintain good email deliverability. Allowing users to opt-out of your email communication ensures the users are not frustrated by unwanted emails; otherwise, the user can report your emails as spam which can impact your email delivery to other users.

To access this feature navigate to Settings-->Mail Settings –>Customise unsubscribe page/link