If you have filed the 2021 tax return then you will have to amend the 2021 tax return to enter the changes from the W-2C.
Note - If the W-2C only changes the Social Security taxes withheld you do not need to amend the 2021 return
An amended return, Form 1040-X, can only be printed and mailed to the IRS if the original tax return was not e-filed. The IRS will take up to 16 weeks or longer to process an amended tax return.
Before starting to amend the tax return, wait for the tax refund to be received or the taxes due to be paid and processed by the IRS.
See this TurboTax support FAQ for amending a 2021 return - https://ttlc.intuit.com/community/tax-return/help/how-do-i-amend-my-2021-return/00/2544441
There is not a separate place to enter a W2-C on its own.
If you have not yet filed your return and you have a W2-C to enter, then you will Edit the original W-2 information and enter the corrected information.
After you have entered the corrected information, there will be a follow-up screen titled Let's check for uncommon situations with selections you can make. Check the box beside W-2 was corrected by my employer (form W2-C).
As stated by Champ DoninGA, if you did already file your return, you will need to amend it in order to take the corrected W-2 into account. You will still simply edit the W-2 that was entered and include the check box as described above.