TECHNICAL REQUIREMENTS MODEL WORK WITH CGTRADER

Show us wireframe, it will be hard to tell it is posible or not.

You need to clean your mesh, removing polygons where they are not necessary.
I'm not an expert, but that's what I've been taught;)
An image might be more understandable :)
https://i.postimg.cc/NjP63Zmh/Sans-titre.png

Hoping it will help you.

if you use blender . so you can use un- subdivide .

i would say that you should bake texture maps for details and make big shapes with polygons