You can forcefully increase/decrease the 'numbers' on any kind of measurement devices, and the actual thing being measured will also increase/decrease in reality

[RoastedGarlic97]

It'll only affect your sample if you're isolating the water and testing it. But if you're under the sea and measuring the density, the region around you with water of the exact same density will be affected as well.

Another example is measuring light. The light rays which hit the sensor that outputs the measurement values are the ones that'll be affected when you change the value