Can I gift money to my 2 kids for a tax break? and if I can, would my kids have to show this as income on their taxes? also, my kids are 16 and 21, do their ages matter?

There is no tax break for gifting money to your children.

Gifts given to an individual are not reported on nor deductible on a tax return.  

Gifts received from an individual are not reported on a tax return, regardless of the amount received.

If the gift given to an individual is greater than $15,000 (2018) then that gift given is to reported to the IRS on Form 709.

Thank you very much.