I think the term you are looking for is "three-quarters isometric overhead." I was hired to build the client for a game in this style, some eleven years ago, now (different camera angle, but still isometric):



This is typically done by overlaying tiled sprites. However, you can approach this effect in 3DGS by playing with the camera's arc and position. For example...

camera.arc=130

...will give you a zoomed-out fish-eye view, with accentuated perspective, whereas...


camera.arc=60

...will give you a zoomed-in view with less perspective. I believe that, mathematically speaking, an isometric view could be achieved by setting camera.arc to 0, (where there will be no perspective) -- however, at that point, the camera's Field of View doesn't exist, and you won't see anything.

Try setting your camera arc low, and moving your camera's position far away from the subject matter.