I used a combination of Unreal Engine, Blender and Photoshop for this.
In Unreal Engine I used pre-made assets like a Building Generator, various materials, foliage, sandbags, the tanks and the ship as well as the MetaHuman tool. The building on top of the hill I constructed more freely, with edited Quixel assets. The towers I constructed in Blender using basic shapes before overpainting the image in Photoshop.