Font color, like font type, is an essential design element. Colors convey emotions to a special extent. Therefore, it is important to stay consistent and not use too many colors on a page. An inconsistent or poorly coordinated color scheme has an unsettling effect and can downright scare away page visitors. When in doubt: Less is more.
For better usability, it is essential to ensure a sufficiently high contrast ratio. Only then will the texts be legible effortlessly. Fortunately, contrast values can be calculated for combinations of text and background color. The already mentioned Tachyons framework comes with a mature color table including some high-contrast combinations. If you copy suitable color values from there for your own WordPress site, you can’t go wrong.
Depending on the editor used, it is possible to change the font color in WordPress without using CSS. This usually quickly leads to an inconsistent appearance and is therefore not a good idea. The modern Gutenberg editor offers a viable middle ground. Gutenberg has a predefined color palette that can be adapted to the color scheme of the theme. If you assign one of the predefined text colors to a block, the editor only adds a few CSS classes. This way, the separation of topics is preserved; if necessary, the classes can be overwritten or muted afterwards.
However, Gutenberg also allows you to assign an “individual color” to individual sections of text out of the box. This should be avoided at all costs. Instead of a predefined class name, Gutenberg inserts the individual color as a hardcoded color value per inline style into the HTML code. Shown here as an example: