Unsubscription Link in Success Mail

I want to add an unsubcription link to my success mail from Magento (2.3), but all the variables I tried so far are not generating a link.

{{var subscriber.getUnsubscriptionLink}}

{{var subscriber.getUnsubscribeUrl}}

{{var subscriber_data.unsubscription_link}}

{{var subscriber_data.unsubscription_url}}

{{var subscriber.getUnsubscriptionLink()}

I know this question has been asked several times in the past, but I could not find any helpful answer.

Is it even possible to put an unsubscription link into success mails / transactional mails?

Thank you in advance!