No. The online versions of TurboTax (TT) cannot be used for fake returns. Anything you enter will mess up your 2016 return.
However with the download / CD versions of TT, you can do multiple returns, including fake ones. You may want to consider switching to down load for future years.
In the mean time, this tool is available for estimates https://turbotax.intuit.com/tax-tools/calculators/taxcaster/?s=1
