I have 2 dependents with income.1 is a college student out of state &1 is still living at home.I've filed a personal extension, so do I need to file one for them?

If they have enough income, on their own, to have to file a tax return, then they would have to file their own extension.

You do not report his/her income on your return. If it has to be reported, at all, it goes on his own return. If your dependent child is under age 19 (or under 24 if a full time student), he or she must file a tax return for 2022 if he had any of the following:

1.          Total income (wages, salaries, taxable scholarship etc.) of more than $12,950 (2022).
2.          Unearned income (interest, dividends, capital gains, unemployment, taxable portion of 529 distribution) of more than $1150 (2022)
3.          Unearned income over $400 (2022) and gross income of more than $1150 (2022)
4.          Household employee income (e.g. baby sitting, lawn mowing) over $2300 ($12,950 if under age 18)
5.          Other self employment income over $432, including money on a form 1099-NEC

Even if he had less, he is allowed to file if he needs to get back income tax withholding. He cannot get back social security or Medicare tax withholding.

In TurboTax, he indicates that somebody else can claim him as a dependent, at the personal information section.