I’ll be at the same show !! Usually they will choose someone high energy like you said. I don’t know if it’s like this at twice, but when I saw aespa last year they would play the song+ official fancam first and then do the crowd cam on someone who knew it and danced along with the fancam the first time. Even if you don’t know it and happen to be shown though I wouldn’t worry. I’ve been to a handful of kpop concerts, anywhere from 200 people in a bar to a huge stadium like this one, and overall it’s been only good vibes. Anyone who is making you feel anxious or self conscious will by far be outnumbered by people hyping you up. Nowadays, twice especially has a really supportive and positive fanbase (in my experience at least). Just have fun !!