If you don't prefer the creepier dark form, you can select only one form for your vampire. You can customize the vampire's normal form or dark form as well. You can customize your vampire Sim to your liking, selecting eye color, shape and plenty of other options. This is a normal game function that does not require any special codes or accessing the cheat code command panel. If you want to make a vampire Sim from scratch, you need only visit the 'Add a Sim' option at the left lower corner of the screen in The Sims 4. How to make a vampire in The Sims 4 from scratch Here's how you can create vampire Sims from scratch or turn Sims you already have into vampires, and the Sims 4 vampire powers you'll unlock. There are a couple of ways you can do it with The Sims 4 Vampires expansion. That's why making vampires out of existing Sims is so much fun.
Using cheat codes in The Sims - and most recently, The Sims 4 - is basically a hallmark of the series, so playing around with your individual Sims is nothing new.