iCloud Drive lets you have the best of both worlds: deep storage that provides ... needs to clear out space to avoid your startup volume from becoming too full. It leaves a placeholder file ...
If you see a message that your device's storage is full, it's worth checking out a system option called Optimize Storage, which is designed to work with iCloud ... you how to do just that.
The primary reason I use iCloud+ is to have my files sync between my iPhone, iPad, and MacBook, as I'm constantly switching ...