True color is a display specification that uses a 24-bit value for the RGB color space, resulting in 16,777,216 color variations. The specification provides a method for storing and representing image information using the RGB color space in such a way that a very large number of shades, colors and hues can be defined in an image, which results in images and graphics with very high image quality and complexity.
Techopedia explains True Color
True color is an RGB color model standard that specifies 256 shades for red, green and blue spaces, totaling 16 million colors, much more than what the human eye can distinguish, which is only 10 million colors. This allows for very complex graphics and images, hence the name.
True color also refers to displays or screens that use the RGB display mode and do not need a color look-up table. Each sub-pixel of red, green and blue contains 8 bits of information, and if a fourth byte is present it is used for alpha channel information or simply ignored. If a system has a fourth byte for the alpha channel, this is then referred to as a 32-bit true-color display, which uses the RGBA color display, where "A" is the alpha channel. If a 32-bit display is forced to revert to a 24-bit mode, then the alpha channel is dropped, which disables transparency and translucency effects but has no effect on the color depth, unless it goes further down towards an 8- or 16-bit color depth.