You only need to enter your W-2 for 2019 in TurboTax 2019. Your refund is based on the Federal tax due and the Federal tax amount withheld. The refund can be increased by any credits you qualify for such as Education credits (Am. Opp. Credit or Lifetime Learning Credit), Earned Income Tax Credit (must be low-income with dependent), and Child Tax Credit. If it's just you, your refund is tax owed minus tax withheld.
