Downgrade Membership to previous plan upon expirat

I would like to have a members subscription "downgrade" to a different plan when their Paid Subscription expires. Can this be done?

I am new to this, but could you have another Joomla Group that is available to the downgrade plan. When the Upgraded plan expired it would just add them to the downgraded Joomla Group allowing them to access the downgrade plan.It would remove them from the group associated with the higher plan.

Clear as mud I know, but I think you may be able to do it via the Joomla Groups.

So clear and so simple.
THANK YOU SO MUCH!!!!!