This is/will be used for something else (and is experimental, as evidenced by the enum name), and at the moment, doesn’t do anything, as you saw.
You can either disable the component, and update it manually.
animator.enabled = false;
then
animator.Update(deltaTime);
Or you can set the speed to zero, and do something like this when you want to update:
animator.speed = 1.0f;
animator.Update(deltaTime);
animator.speed = 0.0f;
Both will give slightly different results, and it depends what you want to do.
The second one will animate every frame, but time will not advance.
This also works with the state machine visual debugging, whereas disabling the animator will break the visual debugging.
It’s also worth noting that using any of those approaches means your animators will run single-threaded, so there may be performance issues.