Will a screen replacement fix black lines down iPhone 6S screen?

A dropped my iPhone 6S a while ago and cracked the screen but never got around to getting it repaired unfortunately. Last time I went out and must have dropped it again as there are now 3 thin black lines running top to bottom on my screen. The phone still works perfectly.

One friend advised me that this happened to her phone shortly before the whole screen went black and it's an internal error, meaning it won't be fixed by replacing the screen. However another friend said this happened to hers and a new screen got rid of the black lines.

I've tried restarting the phone by holding both the power and home button but it had no effect. I'm now looking to get the whole phone repaired, should I make an appointment for a screen repair at an Apple store or is this more likely to need other repairs?

Thank you in advance 🙂