Hi @huwrowlands
You can always query the post by the date. That way, you can loop trough the returned posts and set them as a draft. To learn more about the query, please take a look at this page: https://www.advancedcustomfields.com/resources/query-posts-custom-fields/.
Don’t forget to execute it using the cron job like Wstaley said. This page should give you more idea about it: https://www.smashingmagazine.com/2013/10/schedule-events-using-wordpress-cron/.
Thanks 🙂
