I don't know if I was asked before
But... will your Male Alicorn O.C. have Princess Celestia Body and Mane ?

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the answers to your question are no (because in my AU the size increase is a permanent enlargement spell cast long ago by her that she has to manually turn off (real size is only a little bit bigger than Big Mac)) and yes (provided you mean the blowing in an unseen breeze) in that order.

He's not that well versed in magic as his mother (by choice) so he doesn't have the ethereal hair yet. He prefers mastery over the sword and weapons of war to the arcane.