iPhone 15 - Signing out of iCloud crash

My partner just sold her iPhone 15 online and is now worrying that she did not clear all the data. She signed out of her iCloud account then the phone froze and went back to the factory settings ‘Hello’ screen.

When googling answers it seems that she should have had a screen appear which asks if she wants to keep her local data or not, this screen did not appear as the phone froze. Does this mean she has just sold it to someone who can access all of her data?