yes, I own and use the one sold in the Apple online store, and it works well:
Belkin USB-C to Gigabit Ethernet Adapter - $29.95
The Belkin USB-C to Gigabit Ethernet Adapter - Apple
Packets going to the Internet are sent through the TOPMOST, working interface in the list at:
System Preferences > network
Use the gear Icon under the list to "set service Order' and drag Ethernet TopMost.
When Ethernet is not plugged in, it will be deemed not working, and the next one down the list (typically Wi-Fi) will be used instead without a fuss.