It really depends

1. How widely used is the thing you want to use. For example it hallucinated caddyfile keys when I asked it about setting up early data support for a reverse proxy to a docker container, luckily caddy docs are really good and it was an issue with the framework I use anyway so I had to look it up myself after all. Ig it'd have been more likely to do this right at first attempt if say I wanted it to achieve that using Express with Nginx. For even less popular technology like Elixir it's borderline useless beyond very high level concepts than can apply to any programming language.
2. How well documented it is, also more widespread use can sometimes make up for bad docs.
3. How much has changed since it was trained. Also it might still include deprecated methods since it doesn't discriminate between official docs and other sources like SO in it's training data.

If you want to avoid these issues I'd suggest to first read the docs, then look up stack overflow or likely name of a function you need to write on grep.app, then use a LLM as your last resort. Good for prototyping usually, less so for more specific things.