Need to format text inside a Forms Text Field

Text formatting in an AcroForm text field is implemented with "Rich Text".  Setup the field to be multi-line and rich text. Then when the user is typing text into the field they can select both paragraph and font properties for any, or all, of the text in the field.  These parameters are set from the  "Properties Toolbar", which is access from the right click dropdown menu on the main Acrobat Toolbar, or pressing Ctrl-E.

Numbered lists are not one of the options, but hanging paragraphs are. 

A subset of rich formatting parameters can be set through the scripting model. You can use this to automatically format the text for a numbered list. It's a somewhat complicated process, but unfortunately the text-indent property needed for the hanging paragraph setting is not available in JavaScript. 

Basically, this feature is not practical in PDF forms.