Yes, you can, though TurboTax FreeFile is not an option for prior year taxes. See
https://turbotax.intuit.com/personal-taxes/past-years-products/
for the pricing of 2018 TurboTax software.
That said, there may be lower cost options for preparing your 2018 tax return. A quick Google search brings up https://www.freetaxusa.com/file_2018_income_tax_return.jsp as one example. Another possibility is the free tax self-preparation assistance being offered remotely through the AARP TaxAide program which can be accessed at https://www.aarp.org/money/taxes/aarp_taxaide/ . And, of course, you can always prepare your own form 1040 by filling in and printing the form https://www.irs.gov/pub/irs-prior/f1040--2018.pdf using the instructions https://www.irs.gov/pub/irs-prior/i1040gi--2018.pdf. (Any related forms can also be retrieved through https://www.irs.gov/forms-pubs/prior-year )
Be aware that any refund due you if you file paper forms will not be processed for several months as most IRS processing centers are basically closed until the pandemic abates. Be assured, the refund will not expire while you wait!
