Can I turn in my phone with a screen lock on?
Can my device that I am turning in for credit, an XR, have a screen lock code I don’t remember?
Question marked as
No. The device must be unlocked and removed from the Apple ID and erased.
If its locked it will not be accepted for trade in.
If you don't remember your passcode, restore it using a device and remove it from your Apple ID.
click here ➜ If you forgot your iPhone passcode - Apple Support
then here ➜ Remove a device from Find Devices on iCloud.com - Apple Support