How to handle 'design X from scratch' when you've never used X?

I've had a few interview scenarios where I'm asked to design a system I've never personally used or built, like 'design Spotify' or 'design a real-time analytics dashboard' when my background is more in auth services. It's intimidating because you don't have direct experience with the core domain. How do you approach these 'design X from scratch' questions for unfamiliar domains? Do you fall back on general distributed systems principles and then try to infer requirements? Is there a framework for quickly understanding the core challenges of such a system without deep prior knowledge? I try to ask clarifying questions but sometimes feel like I'm fishing for answers rather than showing insight.