There are codes for colors used for websites programming, etc. For example, white would be #FFFFFF, I think.
Imagine you want to know code for this color.
I assume you already have a graphic file that contains the color. In my case, I had a file 2022-05-09_16-26-54.png to show you the box above.
Step 1: Open Paint, which is a software program included in Windows.
Click on the bucket button (right next to a pencil icon, eraser icon, right-upper side of the screen). It will get you to the editor colors window, showing you also info such as Hue, Sat, Lum...