How to learn color theory, also I would like to know about color matching and font pairing techniques.
read about the differences between primary colors, secondary colors, complementary colors, the different emotions behind colors, etc. There are many youtube videos that can explain all of this.
For color matching, learn about the Pantone matching system in print media. Learn about Hexadecimal “web safe” colors for electronic media.
There are numerous resources online with more in-depth explanations about color theory and fonts. Ye olde Google will help you out with that. In addition to the points previous comments have mentioned, you can also look into understanding hue, saturation, and the different color wheels (CMYK, RGB, RYB) as a starting point.
For electronic media, you can check out WACG guidelines. This is a resource I’ve personally found handy to help with color matching and text for web viewing:
https://designs.ai/colors/contrast.php. As you add color combinations to the table, it’ll tell you how legible text is based on WACG guidelines.
Hope this helps.