A family of Microsoft word processing software products for creating web, email, and print documents.
Before doing anything, I recommend saving a backup. You can use Undo for Replace actions, but sometimes a backup is just simpler.
Using the Replace dialog, simply specify the 11 point font size without specifying a font unless you have 11 point text that you do not want reduced in size.
This will not reach anything in TextBoxes, Headers or Footers.
You may also want to consider replacing Arial with Arial Narrow.
It is too late unless you have other major editing to do, but this could have been greatly simplified by the author's use of Styles. Then it would have been the matter of modifying your Normal or Body Text style definition. Using Word without using styles is shooting yourself in the foot, especially on big projects.
- https://www.addbalance.com/usersguide/stylesImportance.htm
- https://www.addbalance.com/usersguide/3StylesFormatText.htm
You may still be able to replace certain formatting combinations with styles, but I would recommend doing only after making a separate backup. You can do this much as described by the AI bot with the Replace function using the More and Formatting buttons.