The full path to e-Sword resources on the Mac (at least in macOS 11 Big Sur, but probably in earlier versions as well) is "/Users/[YourUserName]/Library/Containers/net.e-sword.e-Sword-X/Data/Library/Application Support". Of course, replace [YourUserName] (square brackets and all) with the name of your home folder on the Mac.
Note that the "Library" folder is invisible. You can open it in the Finder by clicking on the "Go" menu in the menu bar at the top, and if you hold down the option key the Library folder will appear as an option. Alternatively, you could (in the Finder) choose "Go-->Go to Folder..." and then type in, or copy and paste, the path that I have given (remembering, again, to replace [YourUserName] with your actual user name). Of course, you may know all of this already, but I am giving these instructions, just in case.
Once you have located your resources, you could use AirDrop (that would be the simplest solution), or you can use iTunes. In iTunes, there should be a little square button with a little picture of an iOS device (assuming your iPhone is plugged in) near the top of the window: click it. Then choose "File Sharing" from the left-hand sidebar, and then choose "e-Sword LT" from the list of apps you can share with. Then, simply drag the resources you want into the iTunes window. The next time you open e-Sword on your iPhone, they should show up among your resources. As you have already noted, in Catalina or Big Sur, you would use the Finder, as iTunes no longer exists in these more recent versions of macOS. (I hope these instructions are clear enough, I'm just going from memory, as I have the latest macOS, which, as I said, doesn't have iTunes). Like I said, the easiest way is to AirDrop from your Mac to your iPhone, and you don't have to have Catalina or higher to do it.
There is, to my knowledge, no way to directly access the file system in iOS.
Hope this was helpful.
Edited by modulist, 11 June 2021 - 08:50 AM.