Can you tell me where I can download a free template for Christmas flyers? What can you advise me?

Templates for Christmas cards to find as it seems to me is not as difficult as it seems, as I have looked, but many of them or of poor quality or not free. Have you looked at this site https://free-psd-templates.com/category/free-psd-flyer-templates/free-christmas-new-year-flyer-templates-psd/ ? I recently found it and it turns out there are a lot of templates for Christmas themes that you can also use in the creation of leaflets.
I think my advice would be useful to you. Good luck!

Try to create them yourself, it is not difficult and you get something really unique.

Try free graphic designing apps like Canva etc.