My team is making a racing game so we require someone who can make the layout (terrain + roadwork) of an entire map. Usually a race would take 5-8 minutes for one loop, this should give you a scale for how big the map should be.
We are lenient on the time requirement, for the full scale map we expect around a week with updates every couple of days.
You should have decent experience with studio and map building, we already have our assets, so you just have to lay the road and terrain out in a thoughtful way, and then we can place the decoration later.