I am trying to change the form on a button click by forming URL and adding ContentTypeId to it.
It works perfectly fine when the form mode is New or Edit, but when I try to do same for DispForm, it doesn't change the form despite showing new ContentTypeId in the URL.
Below is snippet what I am doing on button click - 

window.location.href=<siteurl>+"/Lists/<ListName>/DispForm.aspx?ID=123&ContentTypeId=<ContentTypeId>";