Do I have to have health insurance in the US if I live overseas ?

There are only a few states in which there is a penalty for not having health insurance.  There has not been federal penalty for not having health insurance for quite a few years.  So, no, you will not face a federal penalty on your federal tax return if you do not have health insurance when you live overseas.

Thanks.

I live in CA. Any CA penalty ?

https://www.ftb.ca.gov/about-ftb/newsroom/health-care-mandate/personal.html