Black level
Black level concerns the darkest part of an image. A monitor's black-level adjustment can change how dark areas look and how their colors balance; some monitors offer separate red, green and blue adjustments. EIZO's display manual
This setting is different from the darkest luminance the panel can physically produce. It is also different from the full or limited color range used by the signal. Raising a black-level value cannot increase the panel's contrast capability, so judge the result by the dark detail you can see.
BetterDisplay shows the controls supplied by the selected controller under Device Control. Their numbers and neutral values depend on the display and controller mapping. Software changes to tones are available separately under Image Adjustments.