Don't know where you are looking. But yes you need to enter the amount you already got to see if you got the right amount or qualify for more.
To get to the stimulus questions in TurboTax at any time, you can search for stimulus or recovery rebate credit then hit ENTER and there should be a Jump to link
If you are trying to trigger it,
Click on Other Tax Situations at top
Click on Let's get started
Answer some questions then Continue
Then click on Let's keep going
Next screen is for the Third Stimulus, if you qualify
