Imagine if maybe, Kylo Ren heard Palpatine was still alive on Endor (or Kef Bir if need be) after all these years, something he might find useful. Maybe Palpatine knows of some secret Imperial something, or secret Sith information, or maybe something something the Force meeting up with the most evil guy will help fix Kylo’s imbalance. His reason for seeking out Palpatine doesn’t matter.
He finds the wreckage of the Second Death Star, and finds Palpatine desperately clinging to life with dark side magic, and maybe a little help from life support maintained by freak show cultists. But for what? He’s completely irrelevant to galactic politics, and his dark influence over the Force has entirely waned. To the rest of the galaxy, he may as well have died way back then, it makes no difference. He’s using up so much effort just to not croak on the spot that he can barely even move his mouth to talk to Kylo, and on top of all this, the unnatural state of his continued existence is diminishing his power in the Force, so eventually he will not be able to keep this up.
Maybe Kylo comments on all this, noting how jarring it is to see the guy who once ruled all of existence and struck terror into the hearts of trillions, or more, without even the control of his bowels. After getting whatever he wanted out of Palpatine, something noted to not even be as useful as he originally thought, he cuts him down with his red lightsaber. All that effort just so he could spend over three decades covered in his own filth.
That would be a pretty cool depiction of the dark side, and what happens to those who devote themselves completely to it.