Can access file saved by a file manager app? (iOS)

### Issue Type

- [ ] Bug Report
- [ ] Feature Request
- [X] Support Question

## Description

## Information
I'm using this plugin to save PDF files to be stored by the user on their device's. On Android, i'm using externalRootDirectory and when using a file manager app, can i access the PDF file and open it.
On iOS, i'm trying to use all of cordova.file.* (from iOS) and i can't find the saved pdf file from file manager app.
Is it possible?

### Command or Code

### Environment, Platform, Device
iOS, iPhone 7

### Version information

## Checklist

- [x] I searched for already existing GitHub issues about this
- [x] I updated all Cordova tooling to their most recent version
- [x] I included all the necessary information above

The issue names cordova.file.* and externalRootDirectory but provides no command, code, versions, test, or repository file to start from. First determine the supported iOS storage and file-manager behavior; done would require a clearly scoped answer or implementation path for accessing the saved PDF.

Written by the indexing model from the issue text.