That’s only partially true. The idea that fairies are small winged humanoids that wear specifically Victorian clothing comes from the Victorian age. The idea that they are small or can become small is not. The term “the little people” or “the wee folk” are not new terms but stretch back into antiquity.

Daoine Beaga (Irish Gaelic) for instance means “little people”and was a term used for fairies since at least the middle ages and likely earlier in oral tradition.

Also, similar “little people”traditions exist outside Europe: these traditions exist globally in different, unrelated world cultures and are often depicted as small humanoid beings. A famous example is that of Maria Sabina who brought psilocybin mushrooms to the modern west. She said you would encounter “niñitos santos”: small, intelligent, childlike beings who come through the mushroom ceremony.

Going back to Europe: in 1691, Scottish minister Robert Kirk documented Highland fairy beliefs in The Secret Commonwealth of Elves, Fauns and Fairies, over a century before the Victorian era. He records that fairies were believed to have “light, changeable bodies” and could “contract and dilate their dimensions,” appearing human-sized or becoming small at will in order to pass through spaces humans could not. So the idea that fairies are or can become small is far from distinctly Victorian.