In The Sims 4 there are still foundations. The big improvement here is that you can add foundations later. So you don't have to rebuild your house if you want a foundation underneath it. You can also determine the height of the foundation, and you don't even need any tricks or cheats to achieve this. It's a built-in feature now. In the Sims 4, I have built a house in Newcrest which has the entire main building on a foundation. I decided to use one of the preset rooms for my back yard.