The experimental “ControlRig” plugin used to have a Rig for the default mannequin, but it was removed in 4.20:
Removed: Control Rig has been completely redone and the previous BaseHuman has been removed and will not work anymore. If you wish to still use the previous Control Rig, this build will break it.
Would anyone like to get together to create a replacement to put on github? I’ve done some IK rigging for VR, and set up some of the twist correctives, but haven’t ever done serious animation rigging.