I didn’t file my 2021 tax then did will filling my 2021 tax returns during 2024 mess up me filling my real taxes for 2024 with dependent

You can prepare 2023 using online TurboTax and you can e-file it.  You cannot prepare 2021 using online, and you cannot e-file it.   Your 2021 return will have to be filed by mail.  They are two completely separate tax returns, prepared using separate software programs, and filed on different forms for the specific tax years.

The current online program can only be used for a 2023 return--no other year.  And if you did not file a 2022 return you will have trouble e-filing 2023.  When it asks for your 2022 AGI try using zero.  If zero does not work then you have to print, sign and mail 2023.

Online preparation and e-filing for 2020, 2021, and  2022 is permanently closed.

To file a return for a prior tax year

 If you need to prepare a return for 2020, 2021, or 2022  you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

You may also want to explore purchasing the software from various retailers such as Amazon, Costco, Best Buy, Walmart, Sam’s, etc.

Remember to prepare your state return as well—if you live in a state that has a state income tax.

https://ttlc.intuit.com/community/state-taxes/help/how-do-i-contact-my-state-department-of-revenue/00/25573 

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.

If you are getting a refund, there is not a penalty for filing past the deadline.  If you owe taxes, the interest/penalties will be calculated by the IRS based on how much you owe and when they receive your return and payment. The IRS will bill you for this; it will not be calculated by TurboTax.