The Federal Form 6251 is the Alternative Minimum Tax form. Intuit has very helpful information on understanding the AMT and its form. Here is the link:

Alternative Minimum Tax: Common Questions - TurboTax Tax Tips & Videos (intuit.com)

You will not yet see these lines on the form in TurboTax because the form is not yet available per this article:

 IRS Forms Availability Table For TurboTax