I've got good news and bad news.
The good news is that if the reader is reading the document using Adobe Reader or Acrobat DC, then a hyperlink to a web page will always open in a new browser window.
However, if the reader is reading the document from within a browser, clicking a hyperlink will always replace the Acrobat page with the URL page.
There's nothing you can do from within InDesign or Acrobat or the browser.
Is there an kind of script I can run in InDesign?