So I’m trying to have a small character on a huge world, so here I gave an example, if the mesh is too small and it has collision bound enabled, then it will float on air and it doesn’t stick to the ground, Any solution for triangle mesh collision bound?
Objects that are set to Dynamic or Rigid Body will use sphere collision bounds by default if you leave the Collision Bounds check-box unchecked. The radius of the collision sphere is equal to the physics Radius value multiplied by the object’s x-axis scaling. It does not take the size of the mesh into account.
In your case, it looks like you want to use Box collision bounds since you have a simple cube. That will take both the size of the mesh and its scaling into account when determining the size of the collision bounds.