There are two forms of text objects.. Point text ( click and start typing) and Paragraph text (click-drag a box, then start typing).
Paragraph text contains a bounding box which can be resized.
Point text has no bounding box, therefore the bounding box can not be resized since it doesn't exist.
If you have point text, but want a bounding box, highlight the text layer in the Layers Panel and choose Type > Convert to Paragraph Text from the menu.
This will create a bounding box around the text by converting the Point Text to Paragraph text.
To alter a bounding box size, insert the type I-beam cursor in the text so its blinking, then hover your cursor over an edge of the bounding box. The cursor will change to an arrow indicator letting you know you can click-drag to resize the bounding box.
You can also convert Paragraph text to Point Text the same way. The Type menu will display a "Covert to Point Text" item if you have a paragraph text layer highlighted in the Layers Panel.