Can we create user defined functions in Couchbase Lite?

I am using .Net core 6 and Couchbase Lite 3.0.2

Can we create user defined functions in Couchbase Lite? if so, Give me sample.

Not sure the user defined functions you are talking about but you are welcome to spend time to explore Couchbase API via Couchbase Lite on C#.Net | Couchbase Docs

I guessed you are asking about custom query function. Couchbase Lite doesn’t support custom function.