So you have built an Image tile set that you have published to ArcGIS Online. It is made up of high resolution imagery (may be 10cm), and as a result you have created a tiling scheme that goes down to level 22 which is a scale of 1:141.
Now you have it on ArcGIS Online. It has published the tiles from .tpk and “The Manage Tiles” dialog clearly shows that the tiling scheme goes to 1:141 but when you load the imagery as a basemap in the ArcGIS Online Map Viewer it only zooms to 1:1128 and nothing you seem to be able to do will change this. What’s going on? Why won’t it zoom beyond 1:1128 even though the image data has tiles that go to 1:141?
The answer to this is relatively simple but not immediately obvious. All Esri basemaps have a maximum display scale of 1:1128 or level 19. When you first open the ArcGIS Online Map viewer it adds an Esri Basemap which contains this setting and so even if you replace the basemap with your higher resolution basemap it will not zoom beyond this scale.
To allow the map to zoom in beyond this scale simply save the Map and exit back to your content page. Then open the map in the ArcGIS Online map viewer again and you will reset the maximum zoom scale and you will now be able to zoom to 1:141 or level 22.