Type Mismatch Runtime Error

I think you must use:

Sub UpdateOptions()

    Dim VisioApp As Object
    Dim vsoPage As Visio.Page

    Set VisioApp = GetObject(, "Visio.Application")

    VisioApp.Windows("Document.vsd").Activate

    Set vsoPage = VisioApp.ActiveDocument.Pages("Model")
       
    If vsoPage.Layers("Option02") = conVisible Then
            excelapp.Workbooks("Spreadsheet").Worksheets("Sheet1").Range("E8").Value = "Yes"
    End If
    

End Sub

if excelApp is valid Excel.Application object.