Hi Micah, yes sir, the CA compliant models will also accept higher capacity magazines.
Stay safe & have a great day!

Hi Micah and welcome. Yes. Most manufacturers including Sig Sauer make 10rd magazine packages so their firearms can be sold in States with magazine capacity restrictions. The only difference is the magazine (10rd) compared to the standard model package higher capacity magazines. The firearm will accept either capacity magazine. Cheers and stay safe!

Yes, the CA version has neutered magazines to be compliant. Both the M17 and the M18 can be equipped with either a 21-round magazine or a 17-round magazine.