After you file

No.  TurboTax cannot review your return to look for mistakes on a past year return.  That is not a service offered or provided by TurboTax.  You can ask specific questions here if you know what the IRS is saying is wrong.   No one can look at your tax return.  No one else has access to your return or your account.

What does the letter from the IRS say about your income?  Do they want copies of your W-2's, 1099"s, etc?   TurboTax does not have those.  TurboTax does not have images or copies of your income documents.  TurboTax has what you yourself entered when you prepared your tax return; TT does not and cannot check your income against outside sources to verify if you reported it completely or correctly.

I RECEIVED A LETTER FROM THE IRS/STATE

TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.

(what the letters from the IRS mean)

I GOT A LETTER FROM THE IRS   

https://ttlc.intuit.com/questions/3605673-i-got-a-letter-or-notice-from-the-irs

I AM BEING AUDITED

If you purchased Audit Defense:

https://ttlc.intuit.com/questions/2924451-i-bought-max-or-audit-defense-and-now-i-m-being-audited

AUDIT SUPPORT

TurboTax has a special phone number for help with IRS/state tax letters, which will be easier than going through regular Customer Support.   At the page below, click on the blue button that says "Get Help from TurboTax Support".  Then it will ask you what tax year is your letter.  Then it will ask you what the letter concerns. Then it will show you the phone number during posted business hours.

https://support.turbotax.intuit.com/irs-notice/audit-support/