Keep all files permanently on the device

Hi all,

on Windows systems you can choose to keep files permanently on your PC.
I failed to find this option on the iOS of my iPad.

Is it possible? Sorry if this question is already answered elsewhere, I did not find an answer.

Im excited also about this topic regarding macOS: If i decided to buy a Macbook - Will it be possible to have all files permanently on the device?

Thanks & regards