For iOS 12 or later you need iTunes 18.104.22.168 or better running on OS X 10.11.4 or better. See How to upgrade to OS X El Capitan - Apple Support if required. iOS 13 likely requires iTunes 22.214.171.124 or better.
Assuming a suitable version of iTunes is in place then in Finder use the menu item Go > Go to Folder..., copy the following text, paste it into the dialog box and press enter:
Unlock your device and connect it to USB. Double click on MobileDeviceUpdater in the folder that has opened. It should notify you of a software update. Install it and iTunes should hopefully recognize your device.