Sims wearing clothes not available in CAS? - Solved

That jacket is an unused CAS part, meaning it's hidden in side the game and is only accessible to NPC Sims on a random basis. It can't be accessed without a mod that unlocks all CAS parts.

ETA: Here's a link to the mod I use to make hidden CAS parts available. I know you can't use mods on console, but you can find the jacket here and it's a good reference in case you see any other Sims in clothes you don't recognize.

https://fogity.wordpress.com/mods/unlocked-cas-parts/