The extension omni.anim.xform_constraint is not available either for Isaac or Composer.
I was wondering then if there’s any way of importing a rigged mesh (from Blender for example) and manipulating the bones accordingly from Isaac without losing the actual constraints applied to the skeleton (tested with one of the characters that comes with Isaac Sim, if you try to rotate a bone, it just deforms the mesh without attending to the actual constraints it should have)