How can I unlock iPhone 13 without a computer that is locked disabled itunes

Have it fixed at an Apple Store or Apple Authorized Service provider or use a friend's computer.

If you forgot your iPhone passcode - Apple Support

If you want to go the Apple Store or AASP router click on the Get Support link at the top right of this page.

Hey there,

If your iPhone or iPad has iOS 15.2 or later installed you can reset it without computer , see: How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

If your phone is not installed on iOS 15.2 or later , you will need a a computer!