Yes, an xtk:form can open the external browser or the IE engine in different ways.
Unfortunately, this is not documented in the JS API forms section of the documentation (neither the JSPAPI.chm nor the Online documentation jsapi-en (so maybe it also means that it is not really supported and could change in new ACC versions without any warnings.)
IE engine but inside AC session, either encapsulated form or pop-up form
The main advantage is that the object/web page leverages the AC session and all of its objects are easily manipulated.
pop-up form: see for example the link Display mirror page in a delivery form, in the broadlogs tab, that displays a pop-up form with underlying IE engine And the definition in the delivery form, search for: <input type="browser" urlMode="true" xpath="/ignored/@mirrorPageUrl"/>
For encapsulated forms (similar of iframe in web pages):
Several uses in ACC user interface, such as for webApp management.
See the xtk:formlib form (library called in other forms) and especially search for "viewer" or urlViewer
See especially the Preview tab of a webApp, firstly the URL field, and below the encapsulated preview page.
One way to achieve is to do the same as the Dashboard tab of a webApp, which is actually a report page so a webApp page encapsulated in the form... (case above)... and it includes a link to the public URL page... that opens in the IE browser.