You have provided no details. In order to claim a non-related person as a dependent on your tax return, that person had to live with you for the entire tax year and have an income of less than $4300 (not counting Social Security.) If they meet that criteria, then you get the $500 credit for other dependents and the 3rd EIP payment for claiming them. The dependent will not receive a 3rd EIP payment, since dependents are not eligible for stimulus payments.
CREDIT FOR OTHER DEPENDENTS
https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...
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