Online is only good for 1 return per account. But you can use the same email address for 5 accounts. How to start another return in the Online version
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-start-another-return-in-turbotax-online/00/25596
Or go to the IRS Free File programs
Free File: Do your Federal Taxes for Free | Internal Revenue Service
The Desktop CD/Download program can do unlimited returns and efile 5. You can buy the Desktop CD/Download program at
TurboTax® 2021-2022 CD/Download Tax Software, Compare Desktop Tax Preparation
Using the TurboTax online editions you can only complete one tax return per account and User ID. If you wanted to start another tax return using the online editions you would need to create a new account with a new User ID.