There is nothing stopping you from writing a game with an isometric
view with XNA. You will either accomplish that by setting a particular camera
position or by creating sprites that use an isometric view.
Both methods are entirely possible with XNA but XNA does not do anything in particular to help you accomplish an isometric view. How you achieve the view is entirely up to you.
You can read more about isometric views here and here. If you're new to game development, then I would recommend going the 2d sprites drawn in an isometric view style method. You can see some examples of that here.
Hope that helps.
Both methods are entirely possible with XNA but XNA does not do anything in particular to help you accomplish an isometric view. How you achieve the view is entirely up to you.
You can read more about isometric views here and here. If you're new to game development, then I would recommend going the 2d sprites drawn in an isometric view style method. You can see some examples of that here.
Hope that helps.