Low contrast between the foreground and background colors can make text difficult to read. Sufficient contrast improves your content's readability, but what exactly does "sufficient" mean?
The Web Content Accessibility Guidelines (WCAG) recommend at least a 4.5 to 1 contrast ratio for normal text. The ratio is calculated by comparing the relative luminance values of two colors. This ranges from 1:1 for the same color, or no contrast, to 21:1 for white against black, the most substantial contrast. There are many contrast checking tools available online that calculate this ratio for you.
Source: https://www.freecodecamp.org/learn/responsive-web-design/applied-accessibility/improve-readability-with-high-contrast-text
Tools: https://contrast-ratio.com/