Q: 4 digit passcode on reset to factory asks for 6 digit passcode

Hi injinuity,

I understand that you've restored your iPhone, and are seeing a screen to enter a 6 digit passcode while you set it up. I know that it's important to have access to your device, so I'm happy to provide some direction to help you out.

To start, check out step 4 of this article, which shows what it looks like when being asked to create a passcode during the setup assistant:

Get started with iPhone, iPad, and iPod touch - Apple Support

Set up Touch ID and create a passcode

On some devices, you can set up Touch ID. With this feature, you can use your fingerprint to unlock your device and make purchases. 

Next, set a six-digit passcode to help protect your data. You'll need a passcode to use features like Touch ID and Apple Pay. If you'd like a four-digit passcode, custom passcode, or no passcode, tap Passcode Options.
 

If this is for unlocking the iPhone, and not something you are seeing during the setup assistant, then check out the steps for resetting a forgotten passcode here:

If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

Thanks for using the Apple Support Communities, cheers!