They can be neutral in their writing if they don’t want you to have high hope and they don’t like you at all. Like “thank you for your time, let me know if you have any more questions”.
Also it depends on the “interviewer”, the admission team member may not have much say as the head of school interviewing you.
Also writing “you will be a great fit here after the interview” is different from saying verbally “you will be a great fit here”.