How to resolve green line issue on iPhone 13?

You most likely have a defective screen

First, try a forced restart. If that doesn't work take it in to the Apple store to have it repaired.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN)

Genius Bar Reservation and Apple Support Options - Apple

You've been given the solution by two people now, there is no problem to solve. You have a defective screen.

You're iPhone 13 is long out of warranty and you will need to get it replaced at your cost.

Thank you for reaching out. 😉

Only a certified Apple technician can determine the cause.

Therefore, I recommend service.

Service Checklist:

• iPhone service pricing.
• Check AppleCare Coverage.
• Get your iPhone ready for service.

Click ▶︎ Start a Service Request.

Need more help?

• United States: 1-800-APLCARE.
• Contact Support.
• iPhone Support.
• iPhone User Guide.

Click ▶︎ Check Repair Status. 🔧

Good luck! 👋🏼😉

Smiliñ 😎 Brian

even if it's their "fault" then that does not change warrenty laws

Legal - Hardware Warranties - Apple

Warranty - Wikipedia

they are not obligated to do anything after the normal warrenty timespan of your country have passed

It’s a manufacturing defect

Are you a certified Apple Genius who has performed a thorough inspection? 🧐

The solution has been provided.

Good luck (again)! 👋🏼😉

Smiliñ 😎 Brian