The rig features IK controls, custom bone shapes, shape key controllers, and various other quality-of-life features to make posing and animating as smooth as possible.
Nostrils, eyes, pupil dilation, eyelids, nictitating membranes, and various facial shapes are all animatable using driver-driven shape keys.
IMPORTANT : Update your blender to version 3.0 (or later) to see the rig
If your computer is not powerful enough you can lower the multires value and still have astonishing results!