There are always new challenges coming up in the marketing industry. The interviewer wants to check whether you are ready for challenges or not. Here is what you can do and say to the interviewer as an answer:  “If I am given content that I have never worked upon before then here is what I prefer doing:  Research on the internet about that form of content.  Talk to teammates who have previously worked on that content format and try to learn from them what strategies do well in that content format.  Network with others in this industry or people who have expertise in that content format and get insights from that.  Plan and draft a strategy based on information gathered and do AB testing to check what works and what does not.”  This is a better approach to this answer instead of directly denying to work on new content formats