How to change single post link color/style?

The Fox comes with a couple of post link styles, like following images:

You can choose/customize post link style in Customize > Single Post > Single Post Content:

If you choose “Black Underline”, It’ll always be black color no matter how you set the link color.

For other styles, you can change link color in Customize > DESIGN > General > Link color. Here you can change the link hover color as well.