Yes, they can already be available in themes via shortcodes. Check out: https://getpublii.com/themes/demo/tattoo/forms/ , https://getpublii.com/themes/demo/mercury/3/forms/ , etc.
Or you could use a third-party forms provider (like Forsmspree.io) and gain the benefits of strong form validation, maybe better anti-spam protection, and so on.
