In the short term, yes, except adapters with multiple ports like apple's USB-c To HDMI adaptor that has both an HDMI port and another USB port to plug in power.

In the short term, yes, except adapters with multiple ports like apple's USB-c To HDMI adaptor that has both an HDMI port and another USB port to plug in power. Long term.. I would expect projectors/displays to supply power to their connected laptop.