Missing shared instance pool/dedicated instance setting

Question

I am trying to understand if a service is set up as a shared or dedicated instance:

https://enterprise.arcgis.com/en/server/10.8/administer/windows/configure-service-instance-settings.htm#ESRI_SECTION1_C10993BA9EC94D6DA0BB87E4EDD0ED31

But I don't see the setting in server manager? What am I missing?

ArcGIS Server 10.7.1 (federated with Portal)

ReeseFacendini · Accepted Answer

Was the service in the screenshot above published with ArcGIS Desktop (ArcMap / ArcCatalog)?  Shared instances are only available for services published from ArcGIS Pro, and all services published from ArcGIS Desktop are dedicated by default.