I'm sure most of us can relate to this, either personally or through our offspring. I know that, as a youngster, I admired several female shoe styles - flattish boots and strappy sandals in particular - and coveted the idea of wearing them as a change from ugly, boring conventional 'boys' footwear - although it never happened (then). And the prevailing fashion for stilettos was not lost on me either, although I fully realised that they were, literally, a step too far. I didn't even have the courage to wear men's cuban heels in the 1960s - I had to wait until almost 2010 before I got any.
My grandson (3 1/2) is mad on tractors, diggers, cranes, buses, trains and the like. But he also quite often puts on his older sister's frilly tutu, Supergirl outfit or sparkly party dress. It is all part of make-believe and play for them both and has no connotations beyond that, as far as I can tell. However, last time we visited, my wife took off her bootees (3.5" tapered heel) and left them in the hall. Said grandson appeared wearing them shortly after - so there may be hope (or not) for him yet!