How to prevent files in my iCloud drive from being automatically sync to my iPhone?

How do i prevent files in my iCloud drive from being automatically sync to my iPhone? I have a 256G iPhone and 2T iCloud storage. When I put a lot of files into my iCloud Drive, through my Mac or iPad, they will be automatically synced to my iPhone. If I cannot manually prevent the download in time and the 256G storage is eaten up, my iPhone goes to white apple! And this happened TWICE!

iOS 15 allow user to optimize storage from drive, but the option is no longer available. Now you can only optimize photo storage.

What's the point to buy a 2T iCloud under this design? To store photos only but no files!? Horrible design!

Someone tells Apple that user need to decide by our own that which folders/files to be synced to device and which to not!