Can I verify my identity here if the IRS sent a letter in in-person? i can not get an appointment

No, you cannot verify your identity to the IRS through TurboTax.

Go to these IRS websites depending on the type of letter you received from the IRS - https://www.irs.gov/individuals/understanding-your-letter-4883c-or-6330c

OR -

https://www.irs.gov/individuals/understanding-your-letter-5447c

IRS Identity and Tax Return Verification Service - https://www.irs.gov/identity-theft-fraud-scams/identity-and-tax-return-verification-service