There are a wide range of “leftist” policies, but they generally include things like higher taxes to support more social services, strong support for labor unions, higher minimum wages, higher government regulation of various aspects of the economy, various social policies including deemphasizing traditional families and religious institutions, etc.

California may not be “socialist” like Sanders wants (and frankly, no country in the OECD is “socialist” anymore the way Sanders wants), but it’s certainly more leftist than the rest of the US. It’s got the highest taxes, among the highest social spending, much more government regulation of the economy, higher percentage of union workers than the US average, the highest minimum wage, etc. If should be doing a lot better than other US states.