I feel like the song flawless in one of the newer mlp episodes should incorporate spanking in some way. They talk of how they learn from their lessons, maybe they should talk about the harsh spanking they got afterwards. Who would give them though? Granny->applejack possible Celestia->twilight but what about others. Maybe the younger sisters do it. Or spike

I think this makes sense to a degree. The Celestia/Twilight relationship makes it simple. Even Cadence might suffice.
Granny> Applejack.
Rarity’s mom seems like the disciplinary type despite her silly appearance in the debut episode.
Same for Pinkie; it’s not hard to see her parents before she moved and Ms. Cake after the fact.
Rainbow Dash and Fluttershy are the hard one because they seem to have over-forgiving parents. As adults I can see both of them asking their friends to help them with that.

Well I guess it can but I don't see much reason for it. I mean it's not easy for me personally to connect the song Flawless with any sort of spanking content I just don't see it there. Though, maybe it depends on how you write this whole situation. Maybe it is possible to make work that particular way.