a way to get stimulus check for dependant adult?

Yes, if he is no longer qualifying to be claimed as a dependent on someone else's return.

He will need to submit the Recovery Rebate Credit Worksheet with is Form 1040. To do this in TurboTax, follow these steps:

1. Go to the search box and enter stimulus. Click the Jump to link.
2. Answer Yes.
3. At the next screen, Let's double-check the amount you received, answer No to edit the first-round and second-round amounts.
4. If no stimulus amount was received, enter 0. An amount should be entered in each box. When finished, click Continue.

For more details about who is a qualifying dependent, see: Who can I claim as my dependent?