It is probably best to begin with the likely high school of attendance, and then look into their specific program. I'm pretty sure that Elk Grove, Monterey Trail, Sheldon, Franklin, Cosumnes Oaks, and Pleasant Grove all run some type of youth program. Laguna Creek used to, but I am not sure of their program status at this time.
There are basically three types of youth-feeder programs in Elk Grove, four if you count "non-existent" as a category. Ask questions of the programs you look into to figure which type they are.
The first type is the independent program that may be loosely affiliated with a particular school attendance area, but doesn't wear the school colors/logo and will have players from a wider area.They often represent areas where the high school doesn't have a feeder program.
The second is the school-associated type where the youth team represents the school in color, logo, and general attendance area, but doesn't necessarily work closely with the actual high school program. Different offenses, defenses, coaching staffs, etc. In this case, the players often form bonds as they progress together and that is a head start for high school team building, regardless of scheme. Often, the high school coaching staffs change during a youth player's years anyway, so learning scheme might not matter much
The third type is the one that is closely affiliated with the high school, including sharing coaching staffs and off/def schemes. I cannot speak for other programs, but I know that Monterey Trail falls into this category. It is a great feeder system as it allows young players to learn the intricacies of the offense and defense years in advance of high school football. Monterey Trail beat Folsom this year in part because Caleb Ramsuer has been running the Veer since he was in elementary school. HOWEVER, learning the Veer doesn't make much sense if the player will not be attending Monterey Trail.
This last type is the best and can be found at many high schools in the Sacramento area. A youth player should live within the attendance boundaries of a program like this and think of it as a years-long commitment to building a community and achieving excellence.
With any of these programs, watch out for the "recruiters," who are usually self-appointed people who take it upon themselves to make all kinds of promises about high school enrollment gambits and future playing time for 9 year-olds. Take all of that in with a healthy dose of skepticism. "Recruiting" elementary school players is a questionable tactic for bettering a program, but there are all sorts of people out there doing exactly that. If someone promotes the positive aspects of their program, that is fine. But when people start trying to "talk" you into joining their program by making future promises and disparaging other programs, watch out. Check out the facts before believing the salesmanship.