I understand that for any specific aircraft, at a constant power setting, you can use the aircraft's attitude as a proxy for airspeed.
For e.g. In aircraft X, when the dashboard is 1 inch below horizon, at power setting X, means the aircraft will be flying at around speed X.
My question is, if you are much higher in terms of altitude, won't your attitude based on visual reference e.g. How many inches away is your dashboard to the horizon, be different when you are much closer to ground?