Just FYI, this is usually one of the things you figure out BEFORE you drive home with your new EV.
No, you can't just add a new 6-20 outlet to that circuit. All of the available power is going to the hot water heater. Even if it wasn't, EV circuits must be dedicated to only charging the EV, not shared.
You need to call an electrician to get the job done more safely than you can do yourself. Note that I intentionally omitted 'right', since I'm jaded as a result of seeing so many 'electrician did X' stories here on TMC.