Of course, you have to dress formally. Banks pay most attention to the image of stability. According to my experience in bank interviews, there are basically no people who don't wear formal clothes. But you don't have to wear it.

Black suit

Because most people who go to face-to-face exams wear dark suits, which gives people a dull feeling. You can choose some other colors, but don't jump too much, as long as it is clean and refreshing.