You can click on the craft-of-matic and choose craft > treats and choose the age up treat.
Once your sim reaches level 6 of the vet skill they are going to unlock the ability to craft the treats you need to age up or age down pets. Magi-Heal’s Medicine Craft-o-Matic and click on it and choose do lab work and your sim will just tinker around with the machine and gain the skill that way. To gain this skill you can use that same Dr. To be able to create the treat to age up or age down pets in the game your sim is going to need to reach level 6 of the veterinarian skill. You can find this item in the vet clinic that is in Brindleton Bay or you can actually purchase one for your home from the hobbies section of buy mode, or by searching the item name. Wow, what a weird name for an item in the game. To be able to age up a pet without using cheats in The Sims 4, you’re going to need access to Dr.
