Can I request the unlock code for Iphone X

unlock it how?

I don't think there are any cases where a simple 'unlock code' gets you anywhere

iPhone disabled?

If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

activation lock?

How to remove Activation Lock - Apple Support

carrier lock?

How to unlock your iPhone for use with a different carrier - Apple Support

Then you must ask the carrier to remove their sim lock.

Apple can not do that.

Then you need to contact T-Mobile to get it unlocked from them.

What do you mean by unlock code? How is it locked?

Only T-Mobile can remove their sim lock.

We don't know it.

Did you buy a used device?