Go to Settings->Forwarder Management and click on the Clients tab. Locate the client of choice and click on the arrow to the left of the name. The information displayed should include the server class(es).
I don't know of any easy way to see which serverclass a host would match other than trying each whitelist/blacklist.
You can look through your deployment servers _internal log for splunkd.log. The entries are given by host IP address (sadly)
For example host with ip 220.127.116.11 matched service class blah and is getting 2 apps myapps_outputs and myapps_inputs
7-07-2021 11:59:03.491 +0000 INFO ClientSessionsManager - ip=18.104.22.168 name=blah New record for sc=myserviceclass app=myapp_outputs: action=Phonehome result=Ok checksum=0 07-07-2021 11:59:03.491 +0000 INFO ClientSessionsManager - ip=22.214.171.124 name=blah New record for sc=myserviceclass app=myapp_inputs: action=Phonehome result=Ok checksum=0