How do I set up conditional formatting?

Hello,

I would like to set up conditional formatting in both the classic form and card form. For example, if a question is answered "Yes", I would like a unique follow-up element to appear. If the question is answered "No", a different follow-up element should appear. How can I add this formatting for both the classic and card form?

You can achieve this using the Show/Hide conditional logic.

Please check out this guide if it suits your requirement: How-to-Show-or-Hide-Fields-Base-on-User-s-Answer 

If you come across any difficulties, please let us know.