How to setup iPhones to backups to other than ‘iCloud?’

There is no option for ICloud Backup to backup to anywhere but iCloud.

Google and Verizon (and possibly others) have their own options but be aware that they are not identical to iCloud Backup.

See for example, https://support.google.com/googleone/answer/9149304?hl=en&co=GENIE.Platform%3DiOS

and https://www.verizon.com/support/apple-apple-verizon-cloud-backup-guide/

You don't.

You can back up to iCloud, or you can back up to your computer.

See the following: Transfer a copy of your iCloud Photos collection to another service - Apple Support

There are a lot of options for photos: Google Photos, Amazon Photos, Shutterfly. Other cloud services such as Dropbox, Box.com, LiveDrive, will offload photos as well as other files. All of them have apps that will automatically sync your photos (and other content) to) to the cloud service.

I'm not aware of any way to transfer cloud to cloud. You'll need to pull the files down to your phone or computer, then upload them to whatever cloud service you want them in.