Is RAG approach suitable for guided question and answering?

I know we can use few shot prompting to give examples of guided/follow up questions. But I also understand that more than 5/6 examples in a few shot prompting is not recommended. In that case, do we actually need to look at fine-tuning and do instruction fine tuning of models. Did anyone work on this type of scenarios. If yes, it will be great to know their experiences and any specific technique followed.