Short answer — the exact dress is the Polo Ralph Lauren striped silk‑blend midi Taylor wore in the engagement photos (posted Aug 26, 2025). You can buy that same style through retailers that ship to Australia, or get a very similar look from Australian labels.

Where to buy the exact dress (ships to/available in Australia)

• Polo Ralph Lauren Striped Silk‑Blend Midi Dress — sold through global stores that offer AU shipping/stock (examples: Mytheresa AU, Revolve/AU listings). (fashionista.com)

Australian brands that make similar halter/smocked striped or silk midi dresses

• Zimmermann — silk, midi and striped styles in the same elevated, romantic aesthetic. (theoutnet.com)
• Aje — Australian label with silk midi and gathered/ruched silhouettes that give a similar vibe. (ajeworld.com)

Tips to find the same look in Australia

• Search for “striped silk‑blend midi,” “smocked/ruched bodice halter midi,” or “halter bias‑cut silk midi” at Australian department stores and boutiques (Myer, David Jones, Farfetch/AU, The Iconic, or the brands above).
• If the exact Ralph Lauren piece is sold out, filter by fabric (silk or silk‑blend), silhouette (smocked bodice + A‑line/midi skirt or halter neck), and color (cream/ivory with black stripes) to find close matches.

If you want, I can:

• Check current Australian stock for the Polo Ralph Lauren dress and give direct retailer links + sizes still available, or
• Pull together 6–8 specific in‑stock Australian alternatives at different price points. Which would you prefer?