Hello,
Are there any packages/extensions/opensource repos that add some auto-sizing functionality to the colliders? Specifically for box colliders, wheel, sphere, etc.
I was going to look into making editor scripts, but if there is anything out there that would save me the hassle I’d appreciate being pointed to it.
Thanks
Box, Capsule and Sphere collider primitives already do auto-size themselves, I think sizing to the AABB for the Mesh you gave at the time you add them.
And if you change the mesh and want to re-auto-size, just choose RESET from the hamburger (context pulldown) on that Component.
As for MeshColliders, you just need to change the Mesh reference in the collider at the same time you change the MeshFilter’s Mesh reference.
If you mean “decompose my arbitrary shape mesh into primitives,” then no, it doesn’t do that. That would fall under the “Hard Problems” category of computationally-indeterminate things. 
I have done things where I produce a lot of small spheres to approximate curved surfaces with spheres… but it was just my own cheesey raycast code applied in a grid.
Okay I’m going to assume you are right, but when I was running through this tutorial, the box collider wasn’t fitting to the prefab and I couldn’t figure out why. I even checked the prefab and there was nothing that would cause an issue. So I guess it sometimes doesn’t work? In this case even though the dog isn’t a straight forward generic model, I would assume it would auto fit to the furthest extents of the geometry. 
Pretty sure it’s your 6.5 scaling factor.