Copy a complet folder from my mac to icloud without using "documents"

If you want, you can choose to use an onlinetool like Dropbox.

If you want to save space on your Mac: have a look at these tips https://support.apple.com/en-us/HT206996

If you do have e.g. a large photolibrary, it helps a lot to move it to an external drive https://support.apple.com/en-us/HT201517

You can drag folders to iCloud Drive, if iCloud Drive is enabled on your Mac and you are seeing it in the Finder. The folder does not need to be in your Documents folder, you can drag to the top level of the iCloud Drive folder. Which system version do your have installed? If you are using macOS 10.15 Catalina or macOS 11 Big Sur, you can save storage by ctrl-clicking the folder on iCloud Drive and use the command "remove download". Then the folder will be only on iCloud Drive, visible on your Mac on iCloud Drive, but does not use storage locally on your Mac. On macOS 10.14 Mojave you can save some storage by using the "Optimise Mac Storage" option in the System preferences for iCloud.

For example - all folders without a colourful icon have been dragged by me to iCloud Drive, outside the "Documents" folder. I rarely use the predefined application collection folders on iCloud Drive, but keep custom folders for other purposes there. The cloud icon with the download arrow is showing, that I have removed the download from iCloud, but not deleted the folder.

To remove a download from iCloud Drive ctrl-click the folder and use "Remove download".

As iCloud is a sync service: if you would copy a folder to iCloud and delete it afterwards on your Mac: it would be deleted in iCloud to.

You can move it to an external drive and include that drive in a TimeMachine backup

The folder will not take up space on your Mac, if you use the "Optimise Mac Storage" option for iCloud Drive and then immediately use the command to remove the download, as shown in my screenshot. The folders showing the cloud with the download arrow are only in iCloud, the other ones are mirrored locally on my Mac. But it requires that you have at least macOS 10.15 Catalina installed or newer. Which system version do you have installed? The older system versions do not allow you to remove the download.