Does USB-C charge your device (laptop/phone) while connected to a plugged-in display?
If you want to run a TV or external display from a MacBook, you need an adaptor. And the Apple USB-C Digital AV Multiport Adaptor has HDMI, USB and USB-C ports, so you can connect the MacBook's power adaptor to the USB-C port while you use the HDMI port to drive the external display. The external display won't power the MacBook itself.