Several state level requirements affect how a website in this market collects data and serves visitors. None of what follows is legal advice, and your attorney has the final word, but a designer who ignores these points leaves you with rework later.
Privacy and consent
California privacy law gives residents rights over how businesses collect and share their personal information. For many sites that means an honest cookie and tracking setup, a clear privacy notice and, where it applies, a visible way for visitors to opt out of the sale or sharing of their data. Analytics and advertising pixels should respect those choices instead of firing before consent.
Accessibility as a daily expectation
Accessibility claims against business websites are common in California, and a site that a screen reader cannot navigate also turns away real customers. Proper heading order, alt text written by a person, sufficient color contrast, labeled form fields and keyboard navigation are planned from the wireframe stage rather than patched in afterward.
Several languages in one region
San Francisco and Oakland have large Chinese and Spanish speaking communities. For a clinic, a legal practice or a neighborhood service, translated key pages can matter as much as the English copy, provided the translations are done by fluent people and each language version is marked up so search engines understand it.