We have TurboTax Desktop (for Windows 10/11) for 2018. You can find it under the 2018 tab here: https://turbotax.intuit.ca/tax/software/prior-year-taxes

We no longer have any TurboTax products available for tax years 2017 or earlier. However, you can still download the forms for those years from the Canada Revenue Agency (CRA) here: https://www.canada.ca/en/revenue-agency/services/forms-publications/tax-packages-years.html