Aging and dying are part of the game, but you can control both. Stopping aging does not even need a code, because there is a setting in the game options. To move a Sim's age forward or back, you use cas.fulleditmode. On the death side, death.toggle turns death off completely, while the ghost traits turn a Sim into a ghost with the death type you choose. Remove the same trait and the ghost comes back to life.
Most codes here need cheats turned on first. See the section on how to open the console.
testingcheats true
Pick the action and the death type, and the command is ready.
traits.{islem}_trait trait_Ghost_{tur}
When reviving, pick the Sim's actual death type. If you pick a different one, the command does nothing.
A game setting that needs no code. While it is off, Sims do not age on their own, and you use a birthday cake to age them up. There are separate boxes for played and unplayed Sims.
Moves a Sim to any age group you like, and making them younger works too. The change takes effect as soon as you leave the screen.
death.toggle true
Brings back the death you turned off with death.toggle false from the basic commands. Sims can die of old age and accidents again.
traits.equip_trait trait_Ghost_OldAge
Turns the selected Sim into a ghost who died of old age. For another death type, change the trait name; the generator on this page lists them all.
traits.remove_trait trait_Ghost_OldAge
Remove the ghost trait and the Sim comes back to life. The trait name must match the Sim's death type, such as OldAge for old age or Fire for a fire death.