You do not need a USB cable connection.
Lightroom (v5.n on a PC) accesses the photos in the Cloud storage ecosystem, exactly the same as the iPhone.
As long as you are signed in (& online) with the same ID credentials, both devices (PC and iPhone) should be showing the same images that are in your Lr Cloud Library.
If you go to lightroom.adobe.com/ in a Web Browser you will see all the photos in the Lr Library.
Be aware that the Lightroom Library and the iPhone Camera Roll are separate photo caches- And it depends on which phone Camera you used as to where the photos are stored.
Lightroom does not 'see' Camera Roll photos unless you 'Add' them to the Lr Library in the phone. (Manually or by an automatic setting).
Regards. My System: Lr-Classic 12.3 Photoshop 24.5, ACR 15.3.1, Lightroom 6.3.1, Lr-iOS 8.0.8, Bridge 13.0.3, Windows-11.