How to get the Base LLM to generate multiple completions

Lesson 1: How does RLHF work, at 3:11, you mention that the Base LLM is “used to generate multiple output completions for the same prompt”.

Question:
How do you do multiple output completions? Is that by asking for more than one completion in the prompt itself? Or is that by some other means like fine tuning or adjusting the temperature or some other way?

Can you tell us the different methods that can be used for generating multiple completions? And the pros and cons if possible.

thanks