The default Mosaico template has unsubscribe option in header. However the token or destination url is for group unsubscribe rather than the more general opt-out token. I cannot see a way to insert/change the token that is used for the default or to change for an individual template.
(1) Is there a way to change an individual mailing to opt-out for unsubscribe (the more common requirement than removing from a Group)
(2) Is there a way to change the default?