Hello, while ArcGIS Desktop (Pro and Map) offer create control over ToC ordering (even feature symbol hierarchy), those all seem ot go away in ArcGIS Online. The attached sees a raster layer posted below vector in ToC show above in East Anglia 1087 2017.
It's even more dramatic when time-aware layers pop above and below each as in Open Northwest Passage? (ref.), see explanation in About.
Any suggestions on how to honor feature layer ordering is appreciated.