IMPROVE LUNAR SCENARIO SHADOWING

Hello everyone, some time ago I had published a discussion to ask for advice on creating a lunar scenario using real high resolution lunar DEM. I solved the problem by creating a mesh inside Blender and exporting it to UE editor as fbx file. The problem is that the rendering results on the shadows are not at all close to those of Blender (engine Cycles). I don’t know if this depends on either scenario resolution or shadowing settings. I would like to improve the resolution and sharpness of the shading (the shadows of Unreal are very blurry and not sharp) and make the shadows static as I get closer to the surface (they change and also a lot about UE and I don’t understand the reason). The precision of shadowing is crucial to the scientific studies I should be conducting by connecting Simulink and Unreal. Do any of you have any advice on settings or plugins to use to improve shadowing ? Reading around I heard about raytracing, distance field shadows. I would like to point out that I work with the UE 4.26 for reasons of compatibility with Matlab/Simulink.
Below I insert images that certify the difference in rendering results between UE and Blender. The difference in sharpness of the shadows is especially noticeable when I approach the surface.

bl shading 3

Thanks in advance for the answers and for the help.

could anyone help me please