Even if you nailed your interview, it’s always a good idea to follow up with some form of communication. It’s common courtesy, and it shows your interest in the position. Each company has their own culture and expectations. If the company seems more traditional and formal, you should consider typing and mailing out a thank you letter. If the company gives off a more laid back vibe, email a friendly thank you note to the team.
Here’s some more tips from Forbes –
Job Seekers: No, The Interview Thank You Note Is Not Dead