Option Explicit

Sub ArrayofArrays()

Dim OuterArray() As Variant
ReDim OuterArray(0 To 0)

Dim InnerArray() As Variant
ReDim InnerArray(0 To 0)

InnerArray(0) = "Foo"
OuterArray(0) = InnerArray

ReDim Preserve OuterArray(LBound(OuterArray) To UBound(OuterArray) + 1)
End Sub

debug.print OuterArray(0)(0)

ReDim Preserve OuterArray(LBound(OuterArray) To UBound(OuterArray) + 1)

Option Explicit

Sub ArrayofArrays()
    Dim tmp As Variant
    Dim OuterArray() As Variant
    ReDim OuterArray(0 To 0)

    Dim InnerArray() As Variant
    ReDim InnerArray(0 To 0)

    InnerArray(0) = "Foo"
    OuterArray(0) = InnerArray

    tmp = OuterArray(0)
    ReDim Preserve tmp(LBound(tmp) To UBound(tmp) + 1)
    OuterArray(0) = tmp
    OuterArray(0)(1) = "Bar"

    Debug.Print OuterArray(0)(1)
End Sub