You have to transfer the 2020 tax return to the 2021 tax return when starting the 2021 return.
See this TurboTax support FAQ for transferring the prior year tax return to the current year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/transfer-last-y...
Note - If you used the TurboTax online editions for the 2020 tax return then you Must sign onto the TurboTax 2021 account with the exact same User ID you used to create the 2020 online account.
