You would need to setup a filter within the AI Search application. So on the Index where you are indexing REQ and INC, update the condition in the search profile.
However are you using Service Portal or Employee Center? Searching for Incidents and REQs feels inefficent and could also lead to some potential performance issues as you are having to index these large tables within AI Search.
Why are you not using OOTB widgets and menus that show users their Incidents and Requests?
I don't see the value of including this in AI Search if I am honest, and just see negatives.
