Cell formats are challenging. There isn't actually a "format" for cells. They include a font (which has a name and size of its own), a NumberFormat, Height, Width, Orientation, etc.
Therefore, you must clarify what you mean by "format.". The font name and size can be found in the code below. You are free to substitute whatever qualities you choose.
The code that follows presupposes that a Worksheet called "Formats" already exists in the workbook. The Font Names and sizes will be listed in that worksheet when you run the macro.
Public Sub GetFormats()
Dim CurrentSheet As Integer
Dim UsedRange As Range
Dim CurrentCell As Range
Dim rw As Long
rw = 1
For CurrentSheet = 1 To Sheets.Count
Set UsedRange = Range(Sheets(CurrentSheet).Range("A1"), Sheets(CurrentSheet).Range("A1").SpecialCells(xlLastCell))
For Each CurrentCell In UsedRange
FontUsed = CurrentCell.Font.Name + ":" + CStr(CurrentCell.Font.Size)
If Sheets("Formats").Cells.Find(FontUsed) Is Nothing Then
Sheets("Formats").Cells(rw, 1).Value = FontUsed
rw = rw + 1