I don’t think any managed AWS service scales well for any bigger enterprise which have to handle a decent amount of traffic. Once you reach certain threshold you soon hit some throttling and limits BS and AWS solution is just to throw more money at them.
DynamoDB scales a lot. It falls into the "throw money at it," bucket though, and you need to have a pattern that shards well with it. If you have a reason they will basically always increase your limits, too.
