How do I keep a local copy of my One drive files on my new iPad Pro so that I can work with them when internet is not available??

I'm a long time Windows user just beginning to learn the Apple environment. With Windows, I have many Excel / Word files that are in One drive that can be accessed off line on my laptop. I'd like this to also be true with these files on my new iPad Pro. I can now see all of my One drive files on my iPad and can successfully edit and save them back to One drive (changes made on the iPad are immkedicately visible on the laptop. But these files are only available to my iPad when I have internet connectivity. How can I store a local copy of these files on my iPad (similar to Windows on laptop) that I can modify when internet is not available? I need some detail on the steps I need to excute on th iPad.