How can I make a bounding box bigger?

I'm sorry for asking this, there seems to be many similar questions and answers... but they don't seem actually to answer the question. (They're usually about scaling or performing transformations on the text.)

In Illustrator CC 2017, I created a text box by dragging the text tool -- upper left to lower right, if that matters. Into that text box, I typed some text. The text is formatted by a Paragraph format. Everything worked as expected.

Then I increased the point size of the type in the Paragraph format. I expected the type to overset the bounding box (indicated by the little red plus sign), and it did. See the image below:

I expected to grab one of the four corner handles, and make the text box bigger to accommodate the re-sized text. When I try this with either the selection or direct selection tools (the black pointer and the white pointer, respectively) I don't get this result. I move the box around, or copy it. I have tried adding various keys such as shift, alt, and control. No resizing effect.

What am I doing wrong here? Is there some other method I'm not familiar with that will make the text box bigger? I'm not so far along that I can't redo everything to make this work right. Note: I don't want to scale the text or perform any transformation on it, I just want to make the bounding box bigger to accommodate the resized text that can't currently be seen. I'm not trying to flow the text into another box.

Thanks for any help.

-j