Encrypting backups if backup application does not support encryption

@Tom, what do you use to encrypt your backups before they leave for offsite backup if the application that you are using to do the backups does not support encryption? Is there an option to run another program that looks at the backed-up data and encrypts what it finds?

For instance, in XCP-NG backups, I don’t see an option for encrypting backups.

what I would like to do is set up syncthing to monitor a folder and then send it offsite, but have it encrypted first.

Thank you!