Quince, the affordable luxury brand that’s gone viral on Instagram and TikTok, is raising about $200 million in a new funding round that values the company at more than $4.5 billion, according to people familiar with the deal. Iconiq, an investment firm that manages the fortunes of Silicon Valley billionaires, is leading the funding round, said the people, who asked not to be identified discussing private information. The new valuation will more than double the company’s previous value — signali...