Man pages matching name mongoc_cursor_set_batch_size in section 3:

mongoc_cursor_set_batch_size.3.en	debian 10 / libmongoc-doc
mongoc_cursor_set_batch_size.3.en	debian 11 / libmongoc-doc
mongoc_cursor_set_batch_size.3.en	debian 12 / libmongoc-doc