The Macbook supports "displays at up to 1920x1200" over HDMI, so that probably wouldn't work. USB-C should theoretically be able to pass 4k @ 60hz via Displayp

The Macbook supports "displays at up to 1920x1200" over HDMI, so that probably wouldn't work. USB-C should theoretically be able to pass 4k @ 60hz via Displayport 1.2, but they don't seem to be releasing a multiport adapter for that. Google released a USB-C to Displayport adapter that might work, but then you'd be on battery power.