Adding a text box to a document is a great way to highlight and easily move relevant information, such as a quotation mark. Adding a text box to a Google Docs file is not obvious to Google.
Adding a Text Box to Google Docs
Google Docs let you add text boxes to your documents to personalize them and highlight specific information, but in a different way than you might expect. To add one, you must first open the drawing tool ̵
Open the Insert menu in your document, and then choose the Draw command. 
Click the Text Box button at the top of the toolbar in the opening drawing window.
Now click with the mouse and drag to create a text box. Then add the text you want.
After you create a text box and add text, you can customize it using the toolbar. Click the three dots to display the extended text toolbar.
Change the color of the background, border, and font, and other formatting options such as bold, italics, bullets, and so on.
If your text box looks the way you want it, click "Save and close" to add it to your document.
You can now move the folder text box to where you want. If you need to make changes, double-click the text box to reopen the drawing tools. Alternatively, you can click the text box that you want to change, and then click Edit.
Although this method is not the easiest way to add a text box to a document, it provides an easy way to insert and edit text boxes throughout your file.