"Flat affect" trait mod?

Hey all! Hope everyone's doing well! I'm looking for a mod that adds a trait that essentially gives your Sims flat affect. Flat affect is, rather simply, where regardless of feelings, your face is often empty or disconnected. There are some characters of mine I'd love to make as Sims, but they never, ever, ever smile -- so I'm looking for a mod that can maybe permanently keep their face, uh... more or less expressionless. Now, I may not want my specific Sim to smile, but I still want other Sims to smile, so mods that remove smiling for every single Sim would not work... hence why I'm looking for a trait. 

I'm also down for any mod that gives you the option to customize how deeply other Sims feel/react to things ( if they get more emotional, or less emotional about things, etc. -- that sounds so stellar! ), like... maybe a slider, so you can make some more emotional, some far less? Maybe just different assignable traits? I dunno. I don't really know what's out there, but any help would be appreciated. ❤️