Configure WLAN as metered or tethered in macOS
It appears that you cannot without a third party extension.

In this question: How does iOS and OS X detect when a Wi-Fi network is a personal hotspot?

There is an answer that describes how OS X detects whether the connection is a personal hotspot and it seems that there is some meta data that's embedded within the signal that identifies it as a hotspot or not.  (There's even some code that checks for if it's a carplay device, too)


  Apple controls the Hardware, the Drivers and the Operating System, I
  guess they can easily add extra metadata when broadcasting the WiFi
  signal so your Mac knows to whether adding the chain icon or not.