Yes, if you use Pure Black wallpapers. Darkish wallpaper won't do cause the pixel is still turned on unlike when you use pure black, the pixels are turned off.
Yes, black and darker wallpapers are less bright making it consumes less battery power. That's also the reason why people prefer using dark mode to prolong the batter consumption.
For devices with OLED or Super AMOLED displays, mostly Samsung Galaxy phones, yes it helps battery and if you're a Dark mode lover this will last little longer
Darker or black wallpapers would indeed consume less battery power in OLED or AMOLED displays. To elaborate more on this, LED displays work by emitting various degrees of light to a pixel. Each pixel contains sub-pixels that filter light through the three primary colors of red, green, and blue (RGB). The amount of light that passes through these sub-pixels (RGB) determines the color of the light emitted to the pixels.
Unlike LCDs that have a backlight, LED displays make their own source of light. This means that if you have a light or white wallpaper, the lights from the LED display will keep turning on and thus consume more power. On the other hand, darker wallpapers will consume less power because they don't require light that much. So if you use a deep black wallpaper, the LED display will not be turned on and won't consume power from it.
I hope this overview on how LED displays work will help you understand this better, v33. Hope you have a wonderful day!
