Hi Sutts, well for a polygon modeler you might check out Silo or Blender.

If you do a web search for "blender terrain", you can find some stuff:

https://artisticrender.com/how-to-use-blenders-free-terrain-generator-ant-landscape-add-on/
https://www.blendermarket.com/products/true-terrain-
https://www.youtube.com/watch?v=Tf9qUs0rqik
https://www.youtube.com/watch?v=jyvbRJJTzY4

- Michael