I doubt there has been significantly more infantilisation in young women’s fashion over the past sixty or seventy years. 20th century ideals, as exemplified by cosmetics and fashion, at least to me, are a clear exaggerated attempt to produce a child-like appearance - rosy cheeks, red lips, healthy clean skin, shiny hair, thin body almost entirely devoid of breasts - and those things as beauty standards for adult women all predate WWII.
Japan on the other hand is crawling with this obsession with cosplay and kawaii and … gah I think it’s almost pathological to the point where there’s such a cuteness overload people become desensitized and abandon their babies for not being cute enough (I kid I kid, but still). To me those images are clearly imitation of the Japanese obsession with coy and exaggeratedly cute, at times Victorian, outfits. In fact, seeing white girls wearing that irks me in that same weird way that Vanilla Ice did when he tried acting Black.