@xxhc1kwagf68 the City Living Expansion Pack is available to buy wherever you buy your Sims Add-ons/Downloadable Content. I'm on Xbox Series X so I buy mine from my Sims 4 home screen that takes me to the Microsoft Store.
You can also buy a download code for it from trusted retailers like Amazon, but make sure you choose the right platform as sometimes it shows you the wrong one. So double check if you do it that way.
It's bound to be on sale somewhere on Black Friday depending on your location.
Here's an overview of the pack:
https://simscommunity.info/2016/11/05/the-sims-4-city-living-review/
It's a really good one, personally I find it essential.