Yes you can, and this shouldn't be surprising.

You can take the output of an LLM and feed it into another LLM and ask it to fact-check. Not surprisingly, these LLMs have a high false negative rate, meaning that it won't always catch the error. (I think you agree with me so far.) However the probability of these LLM failures are independent of each other, so long as you don't share context. The converse is that the LLM has a less-than-we-would-like probability of detecting a hallucination, but if it does then verification of that fact is reliable in future invocations.

Combine this together: you can ask an LLM to do X, for any X, then take the output and feed it into some number of validation instances to look for hallucinations, bad logic, poor understanding, whatever. What you get back on the first pass will look like a flip of the coin -- one agent claims it is hallucination, the other agent says it is correct; both give reasons. But feed those reasons into follow-up verifier prompts, and repeat. You will find that non-hallucination responses tend to persist, while hallucinations are weeded out. The stable point is the truth.

This works. I have workflows that make use of this, so I can attest to its effectiveness. The new-ish Claude Code sub-agent capabilities and slash commands are excellent for doing this, btw.