I apologise if the question is vague, but also I managed to fix it.
Update:
using the base import options produced a model like this.
All the normals and tangents weren’t importing properly, and it was causing really ugly textures and when lit and looked at closer, you could see the polygons.
opening the mesh in the engine, and looking at the LOD0 settings and reduction sections, I was able to improve the quality and remove these problems by recomputing all the normals and tangents, and also using high precision tangents and full UV’s.
so the end result looked like this:
