I am having 2 SP Lists Request and Department leaders. In Power Apps (connecting Request List) after giving Request ID and department Leader field is available with dropdown (Lookup) of Department leaders list. If given Department was not in Department leaders List then it will appear as normal people picker with search option
List1 (Request):
| Request Id | Department | Leader(s) |
| REQ1001 | Finance | Lookup (Department leaders) |
| REQ1002 | Supply Chain | Lookup (Department leaders) |
| REQ1003 | Consulting | Normal People Picker |
List2 (Department leaders):
| Department | Leader(s) |
| Finance | Harish, James |
| Marketing | John |
| Supply Chain | Peter, Sam |

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