Rearranging Data Based on Delimiter

It took some VB code to make it happen. The code is commented as to where you have to make changes to fit the final product.

Basically, the code uses the SPLIT command in VB to sort the parts into an array and then prints one row per array part.

Sub ExpandIt()
Dim i As Long           ' Row index
Dim j As Long           ' Column index
Dim k As Long           ' Array Index
Dim NewDate As Date     ' Date
Dim MyStr() As String   ' Array with input
Dim RowNum As Long      ' Working Row Number
Dim LRowNum As Long     ' Last row for date
Dim sht1 As Worksheet   ' Sheet with the raw data
Dim sht2 As Worksheet   ' Sheet with output

' Change these if you have to
Const StartRow = 3
Const EndRow = 4
Const StartCol = 2
Const EndCol = 6

' Initalize variables
Set sht1 = Sheets("Sheet1")     ' Change as required
Set sht2 = Sheets("Sheet2")     ' Change as required

' Clear the output sheet
sht2.Cells.ClearContents

' Copy the header row
sht1.Range(sht1.Cells(StartRow - 1, StartCol), sht1.Cells(StartRow - 1, EndCol)).Copy sht2.Cells(StartRow - 1, StartCol)

' Loop through the rows
For i = StartRow To EndRow
    NewDate = sht1.Cells(i, StartCol)
    ' Set the last row - start at startrow then calculate after last date
    If i = StartRow Then
        LRowNum = StartRow
    Else
        LRowNum = sht2.Cells(Rows.Count, StartCol).End(xlUp).Row + 1
    End If
    
    ' Loop through columns
    For j = StartCol + 1 To EndCol
        ' Set the Rownum
        RowNum = LRowNum
        MyStr = Split(sht1.Cells(i, j), Chr(10))
        For k = 0 To UBound(MyStr)
            sht2.Cells(RowNum + k, StartCol) = NewDate
            sht2.Cells(RowNum + k, j) = MyStr(k)
        Next k
    Next j
Next i

End Sub

Elaborating on Windknife's formula, here is a shorter formula:

Please try:

=LET(a,C3:F4,b,C2:F2,c,B3:B4,
  REDUCE(HSTACK("",b),SEQUENCE(ROWS(a)),LAMBDA(x,y,VSTACK(x,REDUCE(INDEX(c,y,1),INDEX(a,y,),LAMBDA(m,n,IFNA(HSTACK(m,TEXTSPLIT(n,,CHAR(10))),"")))))))