mine does through State Farm, but I know of other insurance companies where it is an additional amount. Generally you get a $ amount per day up to a certain amount per accident. For for example, $25 with a limit of $750 so that gives you approx 30 days.
I don’t know how lawsuits work in this country – but I could see your income being garnished if you lost.
I’m actually considering adding in a million dollar umbrella policy, just in case. It would cost me about $15 extra a month – something I need to check in any case since my house policy is up for renewal in June.