can i back up my mac to icloud

No, you cannot do that. That is what Time Machine is for. You can use an external attached drive OR a Network access drive to use Time Machine and backup your MacBook Pro.

You can, however, backup your iCloud Drive on iCloud. This is a folder that is created on your MacBook Pro when you subscribe to iCloud. All files in your iCloud Drive folder will be backed up on iCloud, including your Documents folder.

Axel F.

No. iCloud is a file synchronization tool not a backup tool. You can backup mobile devices to iCloud. Use an external drive and Time Machine to backup your computer.