add height at the crown: layered crops, pompadours, high top-knots. keep length past the jaw or well above it — the in-between blunt chin-length cut widens. an angled long bob (longer front, shorter back) carves a diagonal the eye reads as length.
What should a round face avoid with hairstyles?
Flat, wide chin-length bobs and full blunt bangs — both widen the silhouette horizontally.