There are a few ways to make adjustments.
1. You can double click on the Auto-Motion track on the Timeline to open the Auto-Motion Settings panel (or select it from the top toolbar). There you will find a Global Slider to adjust expressiveness.
2. Right click a Motion Clip on the Timeline and choose "Strength" to open the Clip Strength slider.
3. Alternatively, you can double click the Visemes on the Lips track of the Timeline and make individual adjustments there.