In California, the court website explains the basics of jurisdiction for you. https://www.courts.ca.gov/9617.htm Note that in the section on venue, the webpage gives a very basic description of how a case might be appropriate for several different county courts. But what happens when the question is more complex?
Here is a recent Supreme Court case on venue, and how clauses in commercial contracts can trigger venue transfer issues. https://www.scotusblog.com/case-files/cases/atlantic-marine-construction-co-v-united-states-district-court-for-the-western-district-of-texas/? What was the issue in this case and how does it relate to venue? What other venue-related cases can you find?