Legal Question in Civil Litigation in California

There is no law on that. It is governed by the prior lease and/or agreement of the parties. The landlord cannot, however, unilaterally renew a year lease unless the original lease provides that the lease renews if the tenant does not cancel. Likewise the tenant cannot renew a lease automatically unless the lease says they can. Otherwise at the end of the lease it becomes a month-to-month tenancy that is presumed to be on the same terms otherwise as the expired lease.