Did you try what I answered in your other thread (now closed as duplicate threads are not cool here):
For the general text, the CSS selector is:
.widget-container p {
styles go here;
}
Note that you should make CSS changes in a Custom CSS – or a child theme – you can add that function via a plugin such as JetPack. Then add the above code there and add styles as you wish.
For CSS info, this is a good reference site:
https://www.w3schools.com/css/