You should have received a 1099-R reflecting the 401k withdrawal for 2020. If you did not contact your payer and have them forward a copy.
It the withdrawal was in 2021 you will not receive a 1099-R until you file for 2021.
Enter your 1099-R per the link below and TurboTax will guide you through this.
There are several options for the handling of the 401k withdrawal in 2020 due to the CARES act. Please follow the link for CARES ACT benefits
-follow these links for additional information-
Where do I enter my 1099-R? - TurboTax Support
2021 Stimulus: Tax Relief for This Year's Taxes - TurboTax ...