I use borg backup. It, and another tool called restic, are meant for creating encrypted backups. Further, it can create backups regularly and only backup differences. This means you could take a daily backup without making new copies of your entire library. They also allow you to, as part of compressing and encrypting, make a backup to a remote machine over ssh. I think you should start with either of those.
One provider thats built for being a cloud backup is borgbase. It can be a location you backup a borg (or restic I think) repository. There are others that are made to be easily accessed with these backup tools.
Lastly, I'll mention that borg handles making a backup, but doesn't handle the scheduling. Borgmatic is another tool that, given a yml configuration file, will perform the borgbackup commands on a schedule with the defined arguments. You could also use something like systemd/cron to run a schedule.
Personally, I use borgbackup configured in NixOS (which makes the systemd units for making daily backups) and I back up to a different computer in my house and to borgbase. I have 3 copies, 1 cloud and 2 in my home.
Looking forward to TYPE_CHECKING without import typing.