THREEJS displaying drone objects

Hi there. I have multiple drone - pix4d generated .obj files. around 20 of an average 1gig size. I want to be able to display these 3d objects in threejs using the best possible way in terms of permonance and memory. i want to be able to even open these using a mobile browser. I want to be able to see within threejs the terrain in the best way posible , for example i still want to be able to see individual stones on the surface of the ground . I can see these in the original .obj, but these orignal .,obj are too big to load.
Sofar I have learnt and managed to save the .obj as .glb compressed , which has around half the size.

How do i make the files even smaller? , i have heard of transfering the finer details of my terrain to a displacement map/normal map etc, but i cant seem to find the best way . I want the final files to be around 10mb but presenting the same detail when loaded in threejs .

You need to bake the texture of the 3d file using blender so you don’t need normalmap/roughnessmap or nothing only a complete map and export it with glb