Taxes are complicated. And, you're right, there's a "bunch" of "refundable credits" available. But, you need to have some idea of what you might qualify for. What are your circumstances, that makes you think there's something in the tax rules for you.
The money you hear about people getting for just filing a tax return claiming kids requires them to have some earned income (wages or self employment). Without earned income, they are not eligible for the "refundable" Earned Income Credit or Additional Child Tax Credit. Both credits are calculated on the amount of earned income you have. No earned income means no "refund". A small amount of earned income means a small refund. The child tax credit does not "kick in" unless you have at least $2500 of earned income.
There's a new urban myth among college students that says they can get a $1000 from the government just for filing a tax form. For most of them, they simply aren't eligible. A full time unmarried student, under age 24, even if you don't qualify as a dependent, is only eligible for the refundable portion of the American Opportunity Credit if he supports himself by working. You cannot be supporting yourself on parental support, 529 plans or student loans & grants. You usually must have actually paid tuition, not had it paid by scholarships & grants. It is usually best if the parent claims that credit. You cannot claim a credit if you are, or can be, claimed as a dependent by someone else.
For 2020 and 2021, there's the stimulus/rebate credit money. Under the CARES Act, if you are claimed, or qualify to be claimed, as a dependent on someone else’s 2019 return you cannot receive a stimulus check, in 2020. If you qualified as a dependent for 2019, but will not be for 2020, you will most likely get it in 2021, when you file a 2020 tax return. Note that the requirement is not just whether you are actually claimed as a dependent, it's whether you qualify to be claimed as a dependent.
