Can I dynamically create terrain at run time？If so, where I find C++API？
If you want the exact nuances of changing the landscape via C++, its here
https://docs.unrealengine.com/en-US/API/Runtime/Landscape/ALandscape/index.html
However, you want to work in Blueprints. The easiest way to dynamically change terrain at runtime would be use a heightmap and modify the height map. Instead of creating your own derivative of a landscape in BP, you could access the object from the level Blueprint.
To modify a texture at runtime, you could throw it into a material and do wacky functions on it: either by changing a the parameter with a timeline of dynamic material instance OR by using a time node in the material. You could then use a camera to capture the changing material on the cube, and render that texture to render2D target. Now that you have a changing texture, you have to link to the landscape.
How would you go about modifying a height map during runtime? I looked in to the Landscape Import Heightmap from Rendertarget node, but you can’t use that in blueprints anymore. Is there another way to modify a landscape’s heightmap in runtime? Thank you!