Question about boltzmann brains

[Rynn]

From what I understand a Boltzmann brain is a hypothetical brain created by random fluctuations in an isolated system at maximum entropy. I don't think that would be possible in OA because even the archai couldn't make an isolated system of any use. They could create a baby universe near maximum entropy and collapse the wormhole....but that's not actually useful for anything since it's now isolated. But maybe this is just due to my incomplete understanding of a BB. Could you elaborate on how you think one might be created artificially?