Your basic street fashion for people well on in years is pretty kid-based. Baseball hats, shorts, converse tennis shoes, band t-shirts, hoodies seem to be standard for men, even when they are 50-60 years old, and that's exactly what they were wearing when they were 15. (Same band even). Jeans (designer or not), track outfits, fleece, Uggs and all sorts of bad fashion ideas for women too, who should be old enough to know better - so talking with the cis-chicks ain't going to help a lot. (Not that I'm any better, Giants hat, Puma shoes, jeans, band shirt and hoodie is what I'm wearing today). And, true to form I follow people home and here they are, doing well and all that, and the house/apartment looks pretty much exactly like it did when they were in college. (I do better on that regard, my place looks like adults live there most of the time - but I never did any of that when I was young either, so I'm keeping to form). So perhaps it's not so much a second childhood, as the first one never ended - may you stay, forever young and all that.
So, in that they have changed, they might be getting the stuff they really wanted when they were young (No, I don't want a room done in G.I. Joe, I want My Little Pony - or vice-versa) but they are keeping with a general trend that seems to go far beyond trans persons. I just never had very commercial tastes (yeah, I hate Disney, well everything after 1960 or so) and never went that route, preferring my own uniquely bad taste based largely on stuff I find.