Adjust the terrain to a mesh

Hi everyone. I'm relatively new to Unity and C# so I have no idea how to make this work. Basically, I need a script that I would be able to attach to a mesh or a gameobject and it would deform the terrain under it. I need it for creating roads and placing buildings on a curved terrain, also I have a mesh that represents a height map of a terrain and I'd like to match the terrain to it. There are some assets like "EasyRoads3d" and "road architect" that implement that kind of behavior, but the assets have various problems. I tried to look into the scripts of the mentioned assets, but they are too complex for my understanding. So I thought maybe someone here could help me out with a solution. I'd really appreciate it.