Making Collider mesh with less than 255 vertices

Hi,

I have a model which I have bought for Turbosquid which which is made up of 4 meshes. The total count of vertices of all the meshes is around 75000.

When I use put an mesh collider on these meshes, I get errors that collider meshes must have less than 255 vertices per mesh.

I tried to decimate my meshes using decimate modifier in blender to reduce the number of vertices but after doing that my object almost loses its shape.

How do I make a collider mesh with such less vertices?

Is there a way to use collider meshes with more than 255 vertices?