Work with color in every notation: convert HEX ⇄ RGB ⇄ HSL, check text contrast against WCAG and pick lighter and darker shades of your color.
At least 4.5:1 for normal text and 3:1 for large text (AA level).
RGB mixes red, green and blue; HSL describes hue, saturation and lightness — more intuitive for adjusting shades.