DDB is serverless in the sense that you don't have to worry about scalability issues, but you have to worry about design issues[1] if you want to take advantage of everything DynamoDB has to offer. I find dynamo's autoscaling very problematic: It's both slow to kick-in and you can scale down 4 times in 24h, not cost-effective if you have spikes.

[1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerg...