mongoc_database_set_read_concern()

void
mongoc_database_set_read_concern (mongoc_database_t            *database,
                                  const mongoc_read_concern_t  *read_concern);

This function sets the read concern to use on operations performed with database. Collections created with mongoc_database_get_collection() after this call will inherit this read concern.

The default read concern is empty: No readConcern is sent to the server unless explicitly configured.