Hello, everything depends on your job, your position, your motivation for wanting to work part-time, etc. If I don't know more, the scenarios I can provide you are all conjecture. You should carefully analyze the effects of becoming half time on your perks and compensation. Your employer won't fire you for asking to work less hours, but if they are unable to do so and you insist on it, they may do so. It's a little complex since, if you advise resignation, you run the danger of losing your job if you get dismissed.
EDIT:
Forgot to add that this is a "POV" answer.