Is it possible to USB tether an android device using adb through the terminal?

Must have root to change values with setprop, and I am on a Mac OS without a rndis driver so I could not test your method of USB tethering. Another way, if you have the connectivity service (adb shell service list):

The following commands call ConnectivityManager.setUsbTethering(boolean enable) in Android 4.3:

adb shell su -c service call connectivity 34 i32 1 turns on USB tethering.

adb shell su -c service call connectivity 34 i32 0 turns off USB tethering.

For other Android versions replace 34 with the following setUsbTethering calling codes per Android version:

4.4.4: 345.1.0: 306.0.1: 307.0.0: 33

Commands in accepted answer not work on Oreo because now should be additional parameter callerPkg and if put there some random text it works.

int setUsbTethering(boolean enable, String callerPkg);

So, for 8.0 / 8.1 Oreo:

service call connectivity 34 i32 1 s16 text - turn USB tethering ON

service call connectivity 34 i32 0 s16 text - turn USB tethering OFF

It works for me Android Pie with

service call connectivity 33 i32 1 s16 text - turn USB tethering ON

service call connectivity 33 i32 0 s16 text - turn USB tethering OFF

For Android 5.0+ (Lollipop, Marshmallow) use:

adb shell su -c service call connectivity 30 i32 1 to turn USB Tethering ON

adb shell su -c service call connectivity 30 i32 0 to turn USB Tethering OFF

Keep in mind that this requires root.