India, July 28 -- For years, extended-size fashion in India has been limited to a separate section, a handful of styles or basic XXL-and-above clothing. The result is often a poor shopping experience. A shirt may fit at the chest but pull at the armhole. A dress may work at the waist but sit awkwardly at the hip. A kurta may look fine in a standing trial, then become uncomfortable once the customer moves.

Now, a clutch of digital-first brands is starting to treat this as a design, demand-forecasting and inventory problem. Last year, Virgio, a fashion brand founded by former Myntra CEO Amar Nagaram, launched Beyond The Curve, a line for plus-size women.

Rather than simply extending its existing catalogue into larger sizes, Virgio built t...