It depends on the charter school (like the public school) some are glorified daycares but most provide close to a private school level of education. Also like public schools.

At least my kids charter school focuses on college prep, stem and the arts. The classes are small (max 20 kids per teacher) The teachers want to be there (there are no "waiting for summer" shirts worn). And the kids can learn more than one grade in a class. My son is in 3rd grade. His spelling and writing comprehension are on a 3-4rd grade level. But his math and science is 5-6th grade. So he goes to the 5th and 6th grade classrooms for those classes three times a week. And his robot coding is somewhere in the high school level.

There's a few public schools that he might be able to do this, but they are few and far between.