iExplorer for Mac currently can only export calendars and their events directly to the macOS Calendar app. If you don’t want your calendar data added there, you have a couple other options. If you have access to a Windows computer or have Boot Camp or Parallels setup, you could use the Windows version of iExplorer since it lets you export calendars directly to a folder as ICS files, one for each calendar. Or, you could create a new user account on your Mac and use iExplorer there and export your calendars to a new, empty Calendar app. Once they are in the Calendar app, you could then export them as ICS file(s) to a folder by clicking on the Calendar app’s File menu > Export > Export and choose a destination folder. By default, it will export each calendar to your Documents folder.
We plan to eventually offer an option to export calendars to a folder as ICS files like you can in the Windows version, but I don’t have any ETA on when that might be added to iExplorer for Mac. For now, you must follow the steps described in the paragraph above and use iExplorer for Windows or use a new macOS user account.