Casting a laptop's screen with a TV is pretty straightforward This article explains how to mirror a laptop to a TV both wirelessly and using wires and includes instructions to stop mirroring, too ...

If your gaming laptop screen feels too cramped, hook up an external monitor! ... For example, if you plug an HDMI 2.0 cable into an HDMI 2.1 port, it can only operate at HDMI 2.0 speeds.