There is many ways animation problem can be approached.
First of all, there is no character animator on 1.0, which suppose to control legs, body and hands. If that what you need.
For that you either need to wait, roll own solution, or use one of the frameworks from ou fellow developers.
But the way you describe your problem related to DOTS, suggest you haven been working with it before. Which maybe quite difficult for you to make such complex optimal design.
You can reference entities one to other no problem. Usually using LinkedGroup.
But there are other ways too. Specially if you want particles to live after character dies.
Character animationsequencer can be stored on children entities. But you probably want to cash animation sequences on blob asset or relevant. And use entities to store the animation state.
Consider like a baking.
Rendering characters is another matter, when comes into bones. There is thread in DOTS Aninations sub forum. It describes animation options for characters quite well.