@ScottN3389 Thank you for reaching out to us, As I understand you are looking for custom sync attribute (example pager attribute synced from on-premise AD) to be visible in Entra Admin Center.
Attribute which are synced via Directory extension can be viewed via Graph Explorer only.
Reference below screenshot on how to query from Graph explorer
Let me know if you have any further questions, feel free to post back.
Please remember to "Accept Answer" if answer helped, so that others in the community facing similar issues can easily find the solution.