Most airliners have flight deck windows that can be opened in flight.
I own an airplane with a proper roll down window..glass pane too.
Not only do the airliners have open-able windows, but they also have separate and isolated HVAC systems for the flight deck.
Most “smoke in the cabin” problems on jet aircraft come from malfunctioning bleed air fed HVAC equipment. Shutting down the heat and pressurization, and ventilating the cabin with outside air clears the problem, but can only be done below 12,000 feet for any length of time.
A true cabin fire (wiring or other interior equipment burning) is a very dangerous condition on a jet aircraft. Just about every non metal component of aircraft interiore emit very toxic smoke when burned. Turning on the oxygen system very well could make things much worse (by further feeding the fire from ruptured lines) , and ventilating the cabin with outside air may not be able to sufficiently clear the cabin of smoke.