In the Humanoid rig configuration, you can find the Muscles & Settings section, where you can preview and adjust the movement (muscle) range for your character.
You can preview the range of movement in the Muscle Group Preview section by adjusting the sliders (1). You can preview the range of movement per muscle in the Per-Muscle Settings section. You can also adjust the range here by unfolding a given muscle foldout and using the slider (2). In the Additional Settings section, you can adjust more options of your avatar. These are mainly responsible for the flexibility of your rig. You can set how much a bone can be stretched during animation for instance.
The Translation DoF option enables animating bones transition in your Humanoid rig. It is turned off by default, meaning that only rotation of the bones is used in animation.
In the Rig tab in the model import settings, you can find some additional options:
Avatar Definition: This option is responsible for creating a new avatar or copying the avatar from another model. The second option is useful for storing animations in multiple files. It will be discussed further in the Using animations from multiple assets recipe.
Optimize Game Objects: This option lets you hide all bones from the Hierarchy view. The number of game objects in the game has an impact on the performance. You can still choose a number of bones that will be displayed in the Hierarchy. It is useful for having exposing weapon slots and similar gameplay-related bones while hiding others.
Root node: This option is visible only for Generic rigs. It lets you choose the bone responsible for root motion calculation. We will discuss it further in Chapter 4, Character Movement.
