Curious what the use case is of the Update Tiles operation. If you look at this technical article here: FAQ: Is it possible to update tiles in a Tile Service hosted in ArcGIS Online? and scroll to method 3; you'll see that you use the Import Tiles operation to update the tiles of a hosted map service, not Update Tiles... So what does this operation actually do?
The page on the operation: Update Tiles—ArcGIS REST API: Services Directory | ArcGIS for Developers, says it's for updating the extent and cache levels, so I guess it's for a schema change? If you wanted to for example merge a tpk with this existing one that covered a different area at different scales?
Looking for clarification on this, thanks!