The CDS I3 shows class sizes. Of 1272 sections at Brown, 55 are 100+ and 106 are 50-99. But just over 1/3 are 2-9 students, its most populous zone plus another one third 10-19.
Bowdoin has zero at 100+ and four at 50-99 of 402 classes. 41% are 10-19, which is the largest class size
Carleton shows zero at 50+ and four at 40-49 of 335. Over half are 10-19.
Of course each student may or may not experience any of those larger classes and if so, likely infrequently.