You can change the age then. If this is overly bothersome to you, making your Sim(s) younger over and over again, you can also go to Settings, and then Game Options, and then Gameplay, and turn off aging.
Also know, what is the maximum Sim count?
Likewise, people ask, how do you stop a SIM from dying in Sims 4?
You can prevent Sims dying of old age by purchasing the Potion of Youth for 1500 Satisfaction Points. This is fairly sustainable, so long as you continually complete Aspirations and Whims. The earlier in life you take it, the more time there is to get another 1500 to prevent it again.
Can you age down a SIM?
To REALLY age down a sims you need to cheat, there is no other way that I know of. Then click on a mirror or on a wardrobe and enter CAS. The cheats allows you to change everything from your sims including the age. So just select the age you want your sim to be.