Short answer: it was a Polo Ralph Lauren striped silk‑blend smocked midi dress (announced Aug 26, 2025), and you can try Ralph Lauren (may be sold out) or shop very similar styles at Loft, Reformation, Everlane, Madewell, Anthropologie and other retailers. (fashionista.com)

Where to look (good starting points)

• Polo Ralph Lauren — the exact Striped Silk‑Blend Dress is the original; check Ralph Lauren’s site and department stores (it sold out quickly after the photos). (fashionista.com)
• Loft — an affordable close match is the Haven smocked cotton poplin midi (widely recommended as a Taylor‑lookalike). (parade.com)
• Reformation — smocked midi dresses (e.g., Kerrie/Rutherford styles) give the same smocked bodice + A‑line silhouette. (anthropologie.com)
• Everlane & Madewell — both carry smocked midi/poplin styles with the clean, vintage‑inspired look. (everlane.com)
• Anthro / Solid & Striped — good for striped, shirred or smocked midis that echo the engagement look. (anthropologie.com)
• Budget/fast options — media roundups list affordable copies on Amazon, Quince, J.Crew, Hill House Home and others if you want cheaper alternatives. (instyle.com)

Quick shopping tips

• If the Ralph Lauren piece is sold out: set a restock/size alert on RalphLauren.com, check department stores (Bloomingdale’s, Nordstrom, Revolve) and the resale market (eBay/Poshmark). (abc7.com)
• Search keywords to use: “smocked bodice striped midi dress,” “smocked poplin midi,” “striped smocked sundress,” or “smocked A‑line midi.”
• To match the styling: look for cream/black or neutral stripes, smocked/ruched top, removable/adjustable straps, and pair with tan/brown block sandals or espadrilles (that’s how it was styled in the photos). (fashionista.com)

If you want, I can pull current live links and check which sizes/colors are in stock right now (Ralph Lauren and a few of the look‑alikes) and show price comparisons.