Contrast is an important aspect in Webdesign because of its ability to make the user focus. - on things that are more or less important.

How colors make the difference

As you can see in the example below the card with different colored texts is easier to read. That's because the "more important" text stands out due to its high contrast to the white background of the card. The "less important" text is not as showy as the important one so the user focuses on the darker text.

Readability

Especially for long and many paragraphs you should care about readability. High contrast text can handle that. Using light colors (on light background) will only be the better choice when the text is a cite or (as mentioned above) not that important.

Some rules don't apply to your case - Decide yourself wheither it's better to use them or not.

I'm from Germany so English isn't my main language. If I messed up, feel free to ask me :D