This is a useful tool that the IRS provides to see if you need to file a tax return: https://www.irs.gov/help/ita/do-i-need-to-file-a-tax-return
Also, these are the general guidelines concerning when you do and do not need to file a return: https://turbotax.intuit.com/tax-tips/irs-tax-return/does-everyone-need-to-file-an-income-tax-return/...
Moreover, if you've had taxes withheld, even if you don't need to file a return, you should file in order to get the refund.
Filing for refunds
Even if you aren’t required to file a return, you still may want to. If you don’t owe tax at the end of the year, but had taxes withheld from paychecks or other payments—filing a return may allow you to obtain a tax refund. You may also be eligible for certain refundable tax credits, like the Earned Income Tax Credit (EITC), which could generate a refund for you. The only way to get your tax refund is to file a tax return.
You may also qualify for the child tax credit if you have $2500 or more of earned income. https://ttlc.intuit.com/community/credits-and-deductions/help/what-is-the-child-tax-credit/00/25961
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You mentioned that you "did not work." The child-related credits are based on income earned by working, so you cannot file a tax return and expect to receive earned income credit, child tax credit, additional child tax credit, or childcare credit if you did not work.
If you had other sources of income like Social Security, investment income, rental income, retirement income, etc. you MIGHT need to file a tax return.
Who has to file?