I can’t speak for all LLMs but the ones I use

• web based LLM cites its sources. You can just click
• coding LLM tends to have obvious sources (for example if I tell it to use a vendor API to do something, I know there's API documentation as the source of truth and the script is just like the example I would previously have found on StackOverflow.com).

And yes, I frequently check its work and iterate through telling it to