One example I have seen is Come Home by RJRhodes. He has a free version and a premium paid version. The premium version comes out earlier than the free version and it comes with extras that the free version does not have.
Thank you for your comment. I could bring one of the Patreon-exclusive subscriptions to Itch.io at a lower cost since they wouldn't include the posts or future polls that would be available only on Patreon. That would be a good idea.