Set Result = connection.Execute(requete)
Do
    For i = 1 To Result.Fields.Count
        Debug.Print Result(i - 1)
        Output = Output & Result(i - 1) & ";"
        Ws_res.Cells(1, 1).CopyFromRecordset Result
    Next i
    Output = Output & vbNewLine
    Result.MoveNext
Loop Until Result.EOF

If not Result.EOF Then 
    Output = Result.GetRows()
    nbcol = UBound(Output, 1) + 1
    For i = 1 To Result.Fields.Count
        For j = 1 To nbcol
            Debug.Print Output(i, j)
        Next j
    Next i
    Ws_res.Cells(1, 1) = Output
Else
    MsgBox ("No Data found")
End If

Function fct_resultat(fichier_type As Integer, Sql As String, rgD As Range) As Variant
 
Dim connection As Object
Dim Result As Object
Dim SaveName As Variant
Dim Wb_Res As Workbook
Dim Ws_res As Worksheet
Dim i As Integer, j As Integer
Dim nbcol As Integer, nbrow As Integer
Dim requete As String
Set Wb_Res = Workbooks.Add
Set Ws_res = Wb_Res.Worksheets(1)
 
Set connection = CreateObject("ADODB.Connection")
With connection
    .Provider = "Microsoft.ACE.OLEDB.12.0"
    .connectionstring = "Data Source=" & ThisWorkbook.Path & "\" & ThisWorkbook.Name & ";" & "Extended Properties=""Excel 12.0 Xml;HDR=YES"";"
    .Open
End With
requete = Sql
Set Result = connection.Execute(requete)
Do
    Ws_res.Range("A1").CopyFromRecordset Result
    Result.MoveNext
Loop Until Result.EOF

SELECT bps_codeFonds, Portefeuille, bps_libellePaysEmetteur,
       bps_libTypeInstr, bps_libSousTypeInstr, id_inventaire,
       bps_pruDevCot
FROM [Donnees$] 
WHERE bps_deviseCotation="DKK"  AND 
      bps_quantite<10000 
ORDER BY AuM ASC;

Sub Tester()
    fct_resultat "select * from [Donnees$] where false"
End Sub
'Your Function returns no result, so make it a Sub...
Sub fct_resultat(Sql As String)
    Dim connection As Object, Result As Object, SaveName As Variant
    Dim Wb_Res As Workbook, Ws_res As Worksheet
    
    Set Wb_Res = Workbooks.Add
    Set Ws_res = Wb_Res.Worksheets(1)
     
    Set connection = CreateObject("ADODB.Connection")
    With connection
        .Provider = "Microsoft.ACE.OLEDB.12.0"
        .connectionstring = "Data Source=" & ThisWorkbook.FullName & ";" & _
                    "Extended Properties=""Excel 12.0 Xml;HDR=YES"";"
        .Open
        Set Result = .Execute(Sql)
    End With
    
    If Not Result.EOF Then
        'This copies the content of the entire recordset,
        ' so there's no need to use it in a loop 
        Ws_res.Range("A1").CopyFromRecordset Result
    Else
        Ws_res.Range("A1").Value = "No results"
    End If
    
End Sub