Encryption only for external storage


We have a running NC with storage on the server itself. I’d like to add an external S3 storage, but being offsite I’d like to encrypt this data.

Is it possible to enable encryption only for the external storage?

If I got it correctly in the server security settings I must enable server side encryption but leave Encrypt the home storage disabled, so local data will remain clear while external will be encrypted.
Is this correct?