Q. It asked if I was a full-time student in 2023. Does that include high school student?
A. Yes.
In the personal info section, answer yes to that question if you were a full time student for parts of 5 months or more, including high school.
The purpose of the question is to determine if you are eligible to be claimed as a dependent. Since most high school students are under 19, the question is mostly irrelevant for those in H.S.
Later, in the educational expenses section of the interview, do not check full time if it was only for H.S.