Can we do write-object-if-not-exist in S3 similar to conditional put in Dynamo DB?

I have a use case, where I need to avoid overriding the objects. I do understand that because of the distributed nature of the S3, it might not available. Are there any tricks and hacky way to achieve not to override the object in S3 ?

Dynamo DB is also distributed, but it provides conditional put. Wondering what is the architectural difference between Dynamo DB and S3 ?