This is something I tell a lot of people who are just starting out. The Sims helps you give characters basic traits, it helps you work out their long-term goals, and it helps give you a vague idea of what they look like.
Creating sims and sims houses from the ground up is still something I still do when I’m writing. To date I have a sim of every character I’ve ever written.
Even if you have a good idea of your character in your head and you have most of their personality on paper, it is a whole different thing to sit down and create them in The Sims.
I had already written a 300+ page novel about my most recent characters before I sat down and created their sims, their house, and their love interests. This opened up a whole new world for me description-wise. When you have your character in front of you walking through this house you designed for them and picking things up, picking things to eat, etc. you learn so much more about them.
Giving a sim the same traits and job as your character will give you better insight into how your character will react in certain situations. It could even help you pick out difficult favorites for them. Like their favorite food, favorite music, and favorite color.
For example, after I created my sims, a fire broke out in their house. There were several small children inside. Violet, instead of helping any of the small children, ran outside and saved herself. Jasmine tried to grab as many children as she could and carry them to safety (even though she was only a visitor in the house). And Persephone and Caspian just stared at the fire and did nothing.
The fire nearly burned the entire house down because the fire department didn’t wanna put it out. And that’s how I decided a fire would be how Persephone and Violet’s parents died when they were young.
It helped me work out generally how terrible Violet was as a person. Considering she literally left several children in a burning building. Even though she was directly next to said children when the fire started.
You never know what The Sims will teach you about your characters.