No Need To Opt Out Now!
It COULD be just a coincidence. It COULD also be Divine intervention, though. For many parents now sequestered with their kids at home because of the coronavirus quarantines, its a chance to direct their child's sex education toward their values and circumvent the indoctrination the state of CA wants to impose.
With the unexpected opportunity there comes some new questions such as, How do we define the values we want to teach about sex? How do we express them effectively? In case you have forgotten what it was like to be a teen, a "just don't do it" lecture isn't typically a deterrent to sexual activity. Frankly, neither is "God said so." Even if He did.
Let me suggest there are a few ways to dip your toes in the water. First, be age-appropriate. Your preschooler and kindergartner do not need to the burden of all the ways humans interact sexually, but there is no reason not to talk about how their private parts are specially made for special purpose. Second, and this is important, you want your kids to look forward to great married sex -- the same way they look forward to getting a driver's license. In fact, the parallels are unbelievably helpful.
You would be surprised how a conversation about what skills and character qualities someone needs to be a good driver can lead to a good Sex Talk. Not just "how to operate the machinery" but how could YOUR driving affect other people? For instance, on the road: what kind of driving behaviors are smart, considerate and safe? Using turn signals, pulling into the intersection while waiting to turn left, only using the fast lane to pass, etc. And what about sharing the car with other family members, what kind of behaviors make using the car more enjoyable? Making sure there's a full tank of gas before coming home, emptying out the trash, cleaning the windshield, etc.

Great parallels can follow. The biology of sex is the "how to operate the machinery." But what about discussing how sexual behavior and choices affect others? For instance, how could adolescent sexual activity impact, say, the parents of teens who become pregnant? Their siblings, teammates, youth groups, etc.? Or, future partners of either teen? Will the images and memories of past sexual encounters impede their openness or ability to trust and bond since adolescent sexual activity is rarely associated with long-term commitments.
All you have to do is ask the question, What behaviors would be smart, considerate and safe then?
Please keep in mind that TELLING your child the correct answer does not mean they have LEARNED the correct answer. If you really want the lesson to stick, provide an environment where they can figure it out and demonstrate what they learned.
Don't forget: The repeated experiences of adolescence construct the neural pathways which are hardwired in adults!