ICE took a powered off phone and it was returned powered on and unlocked

iOS 17.6.1 is nearly two years old. I hope you meant 18.7.1 and your friend wasn’t dumb enough to ignore updates for that long. Either way any version of iOS other than 26 is no longer receiving updates for iPhone 15. Tell her to get rid of that phone, buy a new one, and follow this guide. If she can’t afford a new one, factory reset it and follow this guide.