Get an external hard drive, or get a NAS, copy the iCloud Drive files there, and configure Time Machine to back up the iCloud Drive files from there.
More generally: Archive or make copies of the information you store in iCloud - Apple Support
Similar to how Time Machine can back up local files to a local hard disk or SSD, Time Machine can also be configured to use a partition on a NAS as a target for backups, so long as the NAS supports partitioning and Time Machine server.
Or you can copy the files to a partition of your own usage on the NAS, and store a copy of the files there outside of Time Machine.
It’s also possible to use both a local hard disk and a NAS for backups, and Time Machine will alternate among all of the configured targets.
Various NAS configurations can be set up to further archive their contents elsewhere, too;,secondsry backups of the backups, or of the file partitions.