So, I've been looking for sources relating to what Trump said, what DeJoy said and how that aligns with your statement here. Nothing seems to corroborate crippling the USPS and/or rigging elections. Mostly news pundits infer something much more heinous from what either of them actually said (which of course happens on the other side as well). Big scary headlines and opening paragraphs, then the actual quote not saying anything close.
Please, provide a source that has lead you to this conclusion.
So far the responders seem correct. Not that it's been debunked, but that there simply isn't a story in the first place. It is also worth noting I similarly found nothing showing USPS was stable until July next year.