Compatibility summary
You will need a travel adapter in Sierra Leone; plug types used there differ from France.
Plug comparison
France plug types: C E
Sierra Leone plug types: G
There is no common plug type between France (C E) and Sierra Leone (G). You need a travel adapter.
Voltage comparison
France: 230V, 50Hz
Sierra Leone: 230V, 50Hz
Voltage difference is within a range many devices tolerate; check your appliance label.