Once the Text Widget has been dragged on to the Page Builder screen, you can add a title to the widget and content in the body. You do some basic formatting of the text as desired.
If you have a large amount of copy but don't want it to take up too much space, you can tick the 'Make Text Expandable' box at the bottom of the widget and set the height of the widget in pixels.
In the final display, this will compress the widget to the height you've set. Clicking 'More' will expand the box to show all of the copy.
The viewer can also click on the 'Full Text' option to view the text in a full-screen pop-up box as below.