Xcom 2 has a mod pack on the Steam community that gives all kinds of great hairstyles. My two favorites within one mod pack (and the ones my best female soldiers eventually earn) are the "Titania" which is a massive braid as wide as the soldier's waist, which trails almost to their knees, and one which is a high ponytail which then spills out blanketing their entire backs, well down their thighs.

In other games, there's Heavenly Sword, which has a main character who's long red hair I believe gets longer the more she kills enemies in battle. There's several "Tales of..." Anime style games. One recent one had a main character with black hair to her calves.

Unfortunately long haired video game characters (like Garnett in FF9 or Lucia in Fire Emblem) seem prone to haircuts. In Fire Emblem Three Houses, several females undergo unfortunate haircuts during a time lapse sequence, but Sothis, Dorothea, Petra, Edelgard do well. Just don't get your hopes up for Ingrid.