icloud documents taking up space on ipad

If I get : a 2tb icloud storage, and I have a Mac with large hard drive, and an ipad with limited space, how do I use my files on the ipad when needed but stop them from being stored on the ipad permanently (given that it doesn't have the space)?

From what I can see, if I open an iCloud file on the iPad, it downloads the file. That make sense for while I work on it, but once I’m done working on it, I want it cleared from the iPad physical drive, and back

to iCloud (and Mac) only.

I tried talking to support, but they did not have the answer. What am I missing? I can't be the only one with this problem - If I have 1tb of files on the Mac, and a large enough (2tb) icloud drive, what happens with an ipad that only has 128gb and needs occasional access to the files?