View | API Reference | ArcGIS API for JavaScript 4.6
There is a statement that says "When using an Esri basemap, the default spatial reference is Web Mercator Auxiliary Sphere."
This makes me think that it can be changed? I would like to set to 4326. I can set a custom basemap using a layer with that spatial reference but I want that layer on top.
I have also tried setting the center and extent of the MapView with the spacial reference but I do not get what I would expect.