Xcode: How to determine which DeviceSupport is useful?
Yes, Xcode keeps device support files for old devices and it's safe to delete them.
If you want to know which ones are still in regular use, you can check the 'Date Modified' attribute:

or you can connect your devices to your Mac and check the OS version / build number in the Devices window of Xcode:

The arm64e version is for iOS devices with the A12 chipset or above: see the Stack Overflow question Xcode arm64 Vs arm64e and the list of devices with those chipsets on Wikipedia:

Apple A12
Apple A13