My prompt:
isometric castle, 3D, detailed, high contrast, isolated background, highlights and shadows, high resolution, realsitic, octane render, HDR




And if you wish to try different building styles, just change the first few words of the promp, for example, if you want to create a tree-house, try
isometric tree-house, 3D, detailed, high contrast, isolated background, highlights and shadows, high resolution, realsitic, octane render, HDR




And the rest:











