According to the "official" state survey, the center of CA is in North Fork, south of Bass Lake. There is a survey marker there. I suppose if you took a CA map and folded it into quarters that may work, but CA is far from square, and North Fork sure seems to be closer to the CA/NV border than it is from the coast.
If you were to look right down the center of the state, north to south along the 99, Merced sure looks to be pretty close to the center. There is a place on 99, north of Atwater, and south of Livingston, where there are two palm trees that are said to mark the center of 99 N to S at the 99/Sultana interchange. When that section of the highway was developed into a freeway a few years ago, an over crossing was made, and the trees were transplanted. One was placed on either side of the freeway. You can see them on google earth. One in the NW and the other in the SE cloverleaf area of the interchange. And that is probably enough trivial information to last us for quite a while. Sorry I got geeky. 🤓