Sysadmin

If you want an automated system that can protect against ransomware your backups need to be hosted in some way where the backup server has control of the retention and not the client (NAS, local disk, etc are not sufficient). If your NAS supports automated snapshots that can't be deleted by the backup user it can mostly fill this gap but may need to be checked for how it handles snapshots when the disk fills.

For self-hosted solutions I've used BURP, Amanda, and Borg backup in the past but have switched to Proxmox backup server as my VMs all run in Proxmox. You still need to consider full disaster recovery scenarios where both your primary and backup system fail. For this PBS sports both tape and remote server replication.

There are also many cloud solutions that do this automatically. For cloud I would always use them in tandem with some kind of local backup.

For all of these they should have an admin account that has strong protection and doesn't share credentials with any of the primary systems.