85% of what you communicate is not with words. It’s through the tone of your voice, the way you sit and a wealth of other messages that your body involuntarily sends.
Coming across confident
Start with a real smile that engages your eyes by thinking happy thoughts. Maintaining good eye contact shows respect and interest, so look at the interviewer, or camera/teleprompter while speaking. Use an open stance (do not cross arms or legs). Relaxed shoulders (not tense) with limbs “hanging loosely” show relaxed confidence.