Can I use dynamic CMS fields in Webflow schema markup?

Yes — and you should. On a CMS Collection template, add your JSON-LD in the head custom code and bind CMS fields directly inside the script using Webflow's field tokens (the '+ Add Field' option). Bind headline to the item name, author to the author field, datePublished to the date, and image to the item image. One block then generates correct schema for every item in the collection.