Access Your Files on iPhone (iOS) and iPad (iPadOS)
You can keep your files in a cloud folder like Dropbox and use any mobile app that works with plain-text files to access them on your iPhone or iPad. We've heard great things about the app 1Writer.
If you use Dropbox, you can view and edit files directly from the Dropbox mobile app. The editor is pretty basic, but it should work for most cases.