>>364921962
Most people upload their own stuff. Many people here kitbash, commission or even 3D model their own stuff, but many others will simply upload booth models as-is. You can buy or "obtain" these booth packages.
You can also just take existing models and port them into VRChat. MMD models are really easy to do this with, almost any MMD you find just about anywhere can be near-effortlessly put into Unity and uploaded.
It really depends on what you want. Are you looking for anything specific?