That’s tricky, because “conspiracy theory” implies a level of deception that makes falsifiability of anything difficult. Like, if somebody starts chatting me up on the street and I wonder if I’m going to get scammed or jumped, that’s a theory about a conspiracy, but it’s not a conspiracy theory because it only involves a few people and I still can be sure what’s up and what’s down.
Epstein being murdered gets called a conspiracy theory, but if a couple of guards, a warden and a single wealthy instigator were the only participants, and they were really sloppy covering it up, is that really so implausible?