Can anyone please point me where to find line 11 on form 6251 for 2018?

[xmasbaby0]

You would need to access your 2018 return and go through the pdf to find that worksheet  (Alternative Minimum Tax) and then scroll down to the line you want.

https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/270...

You can get a free transcript from the IRS:   

https://www.irs.gov/individuals/get-transcript

How do I get a copy of a return I prepared using desktop TurboTax?

https://ttlc.intuit.com/questions/1900639