Remote Backup of Macs to iCloud?

TimeMachine cannot backup to iCloud. See the following for other options: Backup disks you can use with Time Machine - Apple Support

Apple offers iCloud Backup for iPhones and iPads but not for Mac computers.

It is possible to sync data from a Mac to iCloud if you turn on those options (e.g., iCloud Photos, iCloud Drive including the Desktop & Documents option). Syncing has some of the benefits of a backup (and the benefit of being offsite) but is not the same as a backup. Major differences include the fact that not everything on your Mac can be synced and the fact that if you delete something, accidentally or otherwise, there is only a limited time period (30 days in most cases) during which it can be recovered.

Also see: How to back up your Mac - Official Apple Support

And more information on syncing in:

Set up and use iCloud Photos - Apple Support

and

Access and manage your files in iCloud Drive - Apple Support

and

Add your Desktop and Documents files to iCloud Drive - Apple Support

ClickWheelNotCharging wrote:

I'm a little unclear on this question, so without addressing the limitations of what appears to be a max 2TB storage option for iCloud+:

Can TimeMachine back up MacOS computers to an iCloud+ account in order to maintain a remote backup of essential files on one's MacOS laptop/desktop?

No.

Time Machine backs up to local directly-connected storage, or to local network storage with Time Machine support.

There are third-party backup apps that can back up to remote (hosted) storage.

Mac has no means to back up to iCloud, with the closest Apple tooling to that being the iCloud files and documents storage—which doesn’t provide any backup depth.

Carbon Copy Cloner and SuperDuper! and others have remote backup capabilities, and at least one of the NAS boxes can also perform remote backups of itself.

One other potential consideration here and specifically around malicious modifications is that physically disconnected backups are tougher to compromise; the miscreants have to recognize and outlast the backup rotation cycle depth and this assuming that offsite backups are recycled.