Cornell CS courses are not small. There are about 400 CS graduates per year these days.
https://classes.cornell.edu/browse/roster/SP19/subject/CS shows many CS courses with large numbers of discussions attached to each lecture. However, it does not disclose size of lecture and discussions.
Some upper level courses have only lecture with no discussions. But the classrooms can give an idea of the size. For example, CS 4410 (operating systems) is in Klarman Hall KG70, shown at https://registrar.cornell.edu/spaces/klarman-hall-kg70 . CS 4700 (artificial intelligence) is in Olin Hall 155, shown at https://registrar.cornell.edu/sites/registrar/files/space_images/OLH155.jpg .
UCB class sizes in CS are large as well, since there are about 900 L&S CS + EECS graduates per year these days.
As a practical matter, the difference between “very large” and “huge” class sizes is not significant. If you wanted small class sizes, you would have chosen a much smaller school (perhaps a LAC) where CS is not so popular that the department has to choose between making the class sizes large and keeping interested students out of them.