How do I see about adding more housing units on my property lot

[Don Nguyen]

Hi, I own a SFR rental in the city of San Diego. My parents used to own the next door lot and it’s a triplex with a house in front and 2/2 up down apartment building in back. My lot is identical but only has the house in the front. I was wondering how I would go about finding out if I can build additional units on the lot to turn it into a triplex as well. Any advice on where to start would be helpful. Thanks in advance