I think there is a lot of ground to cover in "RAG". Most of the demos or tutorials online seem to simply use a vector database to retrieve similar documents according to a cosine distance.

I'm now working on a "hybrid" search combining lexical and semantic search, using an LLM to translate a user message into a search query to retrieve data.

As far as I know, there's not a "standard", the field keeps moving and there are no simple answers.