Short answer: You might not need Redux but you should understand the concepts.
Long answer: Consider you are building an application and you want other developers to understand the logic without your help. Also, as you application becomes bigger, maintaining the states will becomes a nightmare as setting the state gets out of hands very quickly. You maintain internal states inside the components and then send those states as props to other components which needs those.
Now, after a good one year, you come back to your application to fix some issues. At this point, chances are you won't even remember the code and it becomes very difficult to understand which state is modifying a certain prop (to another component) which caused the bug. Have a predictable state container like Redux will help you in this aspect. It will becomes very much clear to you which component is modifying which thing as you can use the time-travel debugger among other stuffs.
Hope this helps!