I don't have letter 6475. I received letter 6419.

Letter 6475 shows the amount of stimulus you received in 2021.   You can check your online account to see if the stimulus was sent to you---or check your own bank records to look for deposits of $1400 per person on your 2020 return.

https://www.irs.gov/payments/your-online-account

If you did NOT receive the 3rd stimulus payment then you need to go to the recovery rebate credit in Federal Review to get it.   It will show up on line 30 of your Form 1040.

Letter 6419 shows the amount of advance child tax credit payments sent to you.

Federal>Deductions and Credits>You and Your Family>Child Tax Credit

The IRS is sending out letter 6419 to you.  It will show the amount of advance child tax credit that you received during 2021.  Enter the information from that letter carefully.   

The remaining amount of CTC that you can receive will show up on line 28 of your 2021 Form 1040.

PREVIEW 1040

https://ttlc.intuit.com/questions/1901539-how-do-i-preview-my-turbotax-online-return-before-filing

Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

NOTE:   The CTC is indeed a “credit” that can be applied toward any tax liability that you would otherwise have to pay as “tax due”  to the IRS.