Got asked something I'd never seen in an interview. Saying "I don't know, but here's how I'd find out" beat bluffing.
Final round, they asked me about something I had genuinely never touched. Old me would've word-salad'd through it hoping to sound smart. Instead I said "honestly I haven't worked with that, but here's how I'd approach figuring it out" and then talked through docs, a small experiment, who I'd ask.
The interviewer visibly relaxed and said that's exactly what they wanted to see. Got the offer. I think we underrate how much interviewers are testing "what do you do when you don't know" rather than "do you know everything." You can't fake knowledge convincingly to someone senior anyway. Be honest about the edge of what you know and show the method.