Does a Thunderbolt 3 to Ethernet male to male cable exist?
I doubt that such an adapter exists.
You can get TB3 to Ethernet dongles from many different companies - there's no need to buy a TB2 dongle and TB2 ethernet adapter.
You can also get very short ethernet cables. There's no need for a 6ft ethernet cable - you can get a 1ft one (or even shorter). They're available at a low price (few dollars).
Remember to take a close look at the specs of your drive before purchasing adapters (you did not include any identifying information). There's a good chance that the FW800 port is actually going to be faster in practice than connecting over Ethernet.
Also if the drive is already several years old (which I gather it is, as I do not think any current Passport product has the FW800/Ethernet combo) - then it is might be more economical to buy a new drive with USB-C. Remember that old drives will fail at some point.