She seemed to get taller when she was first made an alicorn by Celestia, but I don't think she grew at all between the rest of the seasons, until the epilogue where she was somehow Celestia's size.
Did that later increase to full alicorn size happen all at once? Did she achieve something for it to happen? Does she get the power to make alicorns too now? There are a lot of unanswered questions.