How likely is it that the President knows?

If all the whistleblower claims are true, that there are craft developed by NHI, that there are reverse engineering programmes working on crashed craft, then how likely is it (do we think) that each President knows (as each new President is sworn in)? Apologies if this has been asked before, and obviously there’s no way to verify any of this, but I was just wondering if this is all true, and has been kept under wraps for decades, then would each new President know? Each VP? How about the all the joint chiefs? Or perhaps just the airforce chief? Do we think this would be kept secret from each new administration, unless they specifically asked/pressed the defence department /Pentagon for confirmation? Again, it’s anyone’s guess, but I’m curious as to the community’s thoughts on this.