Follow the instructions below to change the color of text in a block.
1. Select text and click on text color in a pop-up:
2. Choose one of the colors offered or click on Custom Color to choose color from a palette:
Also, you can change the color of several text elements across the site at the same time. For that, click on the Site Style in the top right corner of the editor and choose color palette. Click on edit to customize it further:
In the new window change the colors to see which text elements they affect, then click Done: