This will do nothing. CA has a low median property tax rate[1] of 0.74%, which allows rich elites and foreign speculators to buy empty lots of land and let them sit unused for decades while waiting for them to go up in value. This low property tax rate allows rich rent-seekers to buy up properties and then rent them out to people who can't get the big loans the landed aristocracy can. So we now have a record number of young people living with their parents, especially in expensive places like CA. Newsom is rich, as are his donors, as is Nancy Pelosi, and they have no interest in raising the property taxes of the mansions they live in and their investment properties they don't live in.

[1] http://www.tax-rates.org/taxtables/property-tax-by-state