Here's another article that correctly adjusts the monitor, and it's more accurate than the previous one.

Why do we need to calibrate the monitor?

Since the monitor does not resemble the printed materials or physical objects we see; the colors it displays can vary due to different operating systems, monitor brands, graphics cards, varying brightness levels, differing contrast settings, and even different usage environments. Therefore, before doing anything else, we first need to calibrate the monitor so that it can reach a relatively "vivid" and accurate level.

The simplest method for adjusting monitor color is by using Adobe Photoshop's color calibration feature. When you install Photoshop, the software will prompt you to calibrate your monitor. If you don't have Photoshop installed, that's fine too—there are other methods below that can also help you adjust your monitor.