I’ll be homeless soon. Does anyone know a safe place where I can park my car to sleep and a gym i can go to take a shower?

21F, this is going to be a first time for me to live in a car, and I've never slept in my car either. Is it safe to sleep in with all windows closed and engine off? I would greatly appreciate any advice or things I need to be prepared of. I don't have any place to go or can't afford anything, even food. (But I don't really worry about it as I have done fasting for several days before and sometimes there's free food at the place I work at). My car is small and I can't fit in all my stuff in there so I decided to rent a storage ($38/month). I'm working nights and sleep some time during the day ( I have online classes on schedule). Unfortunately the library and gym at my workplace is closed because of covid.