This dialog box appears when you choose a color for a style, or you choose a color for text in an overlay.
Here are ways to choose a color:
Click and drag the color slider control until you see a range of desired colors in the large box above the slider control.
Then, click a place in the top part of the dialog box that shows the specific color you want to use.
You can click and drag the mouse pointer to see the colors change in the small boxes.
Type or paste a hex color code (https://htmlcolorcodes.com/) in the box.
Click a recently used color to use it again.
For example:

Apply direct formatting is different.
The Background Color dialog box is similar.