Yes as its just another link, but not that usable deployed alone.
For example, log in to unsubscribe. I had a few marketing emails does this.
However, when’s your last time clicking the unsubscribe link? I guess most people would mark it spam before unsubscribe, at least I do.
Most attackers will consider more eye catching, urgent, and time sensitive subjects like prizes win, exclusive discounts, or account security warning rather wait one clicking on the unsubscribe link. It is more resonable to add a malicious unsub link with all other links. Actually, all links should redirect the victim to the phishing page.