Inverse Kinematics for non-humanoids

I know this isn't about Unity's IK stuff, but why not just do it in a 3d modeling program? It's simple.

Like example

(Bicep > Tricep > Hand) Drag an IK Chain from Bicep to hand, and they will be able to properly animate like they should.

That's just my 2 cents.

I have the model with bones. It's just that it isn't animating like it should.

What exactly is it doing?

If you animate it in 3d modeling program with your IK Chains it should export all the animations properly.

N1wHead: imported IK is baked-out into FK. In other words, anything you import will have a locked-in animation. Not true IK.

IK can be used for "realistic" movement, if you compute it per-frame in game. This allows the foot to rest on a rock, or depression and have both legs bend properly. Or the character walking properly up/down the exact slope. Or both arms bending properly for a gun aimed anywhere, at any recoil, with any type of grips.