There is a saying, “Dress for the job you want to be promoted to, not the job you’re interviewing for.”
If the Director of Sales wears a suit and tie or business suit to the office, you should wear a suit and tie or business suit to the interview even though you are interviewing for a salesperson who usually wears slacks and an open collar shirt or a skirt and blouse.
Research the company you are interviewing with before the interview and find out what the dress code is. Always dress a little sharper than the normal day to day attire of the company.
It doesn’t hurt to follow this rule on a regular basis if you want to be considered for a promotion. Allow management to visualize you in the new position.