Oh, I actually figured it out thanks to this thread:
https://forums.thesims.com/en_US/discussion/953848/do-you-enjoy-long-lifespan/p1 "EgonVM;c-16903207" wrote:
Yes, I do enjoy that. Especially when I have a mod that allows all the cheats and can use this cheat to make elders die by old age:
sims.age_up
I would like an easy cheat way to age sims up not the blocked way.
So the cheat does exist still, it's just blocked from the game and is meant to only be used by developers. This cheat wasn't blocked around the time Cats and Dogs came out because I used it to kill Justin and Supriya Delgato, but I guess at a later update they decided to block this cheat from being used by most people.
So to be able to use it you need a mod that unlocks the locked cheats. Carl's Sims 4 Guide explains that more so I guess I'll go read that to decide if I want to install that mod or just make my elders hit the gym.
