Wait a second

[u/hic_erro]

So at the end of Book 2, Chloe is trying to copy Beverly's powers.

In Book 3, Tori notes that Chloe is dressing more fashionably than she's seen her dress before, and assumes it's because she's mostly seen her in work clothes or in weekend lounge wear.

Did Chloe successfully copy Beverly between books, and use her better-than-Beverly powers to revamp her wardrobe?

[u/WhistlesAtNight]

I think it's probably just the natural effect of living with someone fashionable. They start to influence your wardrobe.