This question is especially in the context, when we have IN clause in the query, and number of elements in the in clause can be dynamic and huge as per the application needs.
There is no limit on query length. more length it takes more time parse statement. Also can use more memory if statement is stored in system:completed_requests. You can use query parameter also not to increase query length. There is no LIMIT on IN clause limit. The number of elements make difference in query plan time. Check out the https://blog.couchbase.com/in-list-handling-improvements-in-couchbase-server-6-5/ which has all the details.