If you have already prepared a return for 2016 using TurboTax Online - unfortunately, that year has been discontinued, and the files are no longer available. TRA (Tax return access) services were not introduced until 2017, so you won’t see PDFs from 2016 (or earlier) in your account, either.
However, you can still get the information from your 2016 tax returns via the CRA using their My Account service: https://www.canada.ca/en/revenue-agency/services/e-services/e-services-individuals/account-individua...
