On Immigration it truly depends. Low skilled and Illegal Immigration Immigration Benefits Rural Areas far more than Suburban Areas , while High Skilled Immigration benefits Suburban Areas far more than Rural Areas.
Also rural areas are necessarily more anti-immigrant than Suburban Areas, so for example if you consider prop 187 anti-immigrant(I dont) it was Orange County where that prop oriented :
https://www.ocregister.com/2014/11/08/20-years-after-prop-187-oc-group-that-helped-create-it-is-pushing-for-same-goals/In 2006 During the Immigration Debate it was Duncan Hunter and Republicans from Border Counties that stopped it.
I would say Rural Areas are more socially conservative but really dont care about immigration, while Suburban Areas are more polarized on the issue
Lastly Its also not just Suburban CA that changed this is how CA changed as a whole since 2000:
Literally, almost all of CA has trended blue since 2000 and even in the Rural Areas Republicans cant perform the way how they used too back in 2000