What is this "Legacy Devices" feature you speak of ?
That was the same with mine but the options appeared on the other Mac (also a legacy device). What are you trying to copy to or from?Unfortunately the iMac still has High Sierra and does not have those bottom options.
I'm going to try with a USB Bluetooth dongle to see if it does the trick..
Forget iOS with legacy devices. Not an option. By choosing Legacy Devices in the options you disable AirDrop support for iOS.iPhone to iMac.
You access it from a non-legacy OSX device. In my case, it was a Mac Pro 5,1 (2010, so older than the iMac) updated via OCLP to run Ventura and with an upgraded WiFi/BT card. If you want to access stuff on your iPhone via the iMac, then you will need to hook them up via USB and try via iTunes or third party software. Either that or sharing over the cloud: iCloud/GoogleDrive/OneDrive etc.I cannot access the legacy option from a legacy device anyway.