These leggings are made from the Petite Peg Legs pattern from Patterns for Pirates. They're best made with knits like cotton/lycra (spandex), double brushed poly, poly/lycra (usually athletic knits), and nylon/lycra (usually dance/swim knits).
Check our their page for inspiration, there's lots of photos of what people have made.
https://www.patternsforpirates.com/product/petite-pegs/