3,2,1.

My nas is a Synology with raid.

1. Backup with versions to a single large HD via USB. This ransomware protection or accidental deletion. (Rsync)
2. Offsite copy to backblaze b2.One version. (Rsync) (~$6/month) This would be natual disaster protection. flood, fire.
3. Second not raided cheaper Synology at a friends on the other coast. This has ~3 versions. Sorta the backup to the first two.