Changing font type based on conditional formatting

So is there any way I can have a dropdown box with the options, "G/Y/R", and then once the user makes their selection, change the cell contents to be a circle, colored appropriately based on whether the user selected G, Y or R?

You can't do this with the standard Data Validation drop down and it can only be done using VBA code.

If you can use a VBA solution then perhaps the attached will be helpful.
In the attached workbook . . .
An active-X combobox was created using a ListFillRange in column-K.
The code targets column-A. If the activecell is in column-A, then the comboxbox is made visible and presents a choice of G/Y/R. Once the selection is made, the activecell is formatted to the wingding font using the applicable color.

Option Explicit

Private Sub ComboBox1_Change()

With ActiveCell
    .Font.Name = "Wingdings"
    .Value = "l"
    Select Case Me.ComboBox1.Value
        Case "G": ActiveCell.Font.ColorIndex = 10
        Case "Y": ActiveCell.Font.ColorIndex = 6
        Case "R": ActiveCell.Font.ColorIndex = 3
    End Select
End With

    Me.ComboBox1.Visible = False

End Sub


Private Sub Worksheet_SelectionChange(ByVal Target As Range)

    If Target.Cells.Count > 1 Then Exit Sub
    
    If Not Intersect(ActiveCell, Range("A1:A10")) Is Nothing Then
        With Me.ComboBox1
            .Visible = True
            .Top = ActiveCell.Top
            .Left = ActiveCell.Left
        End With
    Else
        Me.ComboBox1.Visible = False
    End If

End Sub