If you want to apply the content type "application/json" only to objects within a specific folder in your S3 bucket, you can specify the folder path in the command. Here's how you can do it:

aws s3 cp --metadata-directive REPLACE --content-type "application/json" s3://your-bucket-name/path/to/folder/ s3://your-bucket-name/path/to/folder/ --recursive

Replace "your-bucket-name" with the name of your S3 bucket and "path/to/folder/" with the path to your specific folder within the bucket. This command will recursively copy all objects within that folder while setting their content type to "application/json".