Mmph. So from experience, I'll mention that you might want to watch out for gendered signage on public or school bathrooms, as well!

On Legos: perhaps you could remove them from the boxes first? Though, of course, the bigger conversation is over age guidelines as ballparks or averages only, not rules set in stone. Like sizes on clothing. If she were a really tall six-year-old, would she refuse to wear size 8 clothes because she was "too young"? If she's on the smaller side, is she "too old" to wear size 4T? Obviously not. If those are the sizes that fit her body, she should wear them; we don't need to be bound by the size expectations for her age. Likewise, these Legos are the "sizes" that fit her Lego skills. (Not that there's anything wrong with playing with "younger" Legos.)
...pronounced like the long vowel and first letter of the alphabet...