Hi vg11
Just to clarify a little. When I say map view, I am referring to `esri/views/MapView` module/class from the ArcGIS javascript library. But the solution should work on both Pro and Web Map.
In ArcGIS Pro, you would redefine the coordinate system in your map project if it hasn't already adopted the coordinate system of the first layer or basemap you started your project with. In Javascript, your would define the spatial reference when create your map object.
However, with javascript, it a bit tricky since if you specify a particular spatial reference on your map object. Other maps layers in different coordinate system do not gets auto-projected, at least in my experience. You would either be unable to add the map layers, or it will rendered incorrectly.