If you are wondering why Kamala Harris went on Fox. Don't underestimate how much of the public watches it - from both parties.
This was a way for her to get a lot of Fox watching Democrats/independents/moderates to see her unfiltered.
It is probably a lot to do with sexism, but some voters have some concerns about her standing up to world leaders and so forth.
I thought she did pretty well all things considered in the interview. I don't know if it will get votes, but I don't think it hurt.