It must be the child's and it can only be funded with the child's own taxable compensation. W-2 wages or self-employed income. Income from gifts are not taxable compensation.
If "you" want to fund it then just open a bank or brokerage account, not an IRA.
The most you can contribute to all of your traditional and Roth IRAs is the smaller of:
For 2019 and 2020, $6,000, or $7,000 if you’re age 50 or older by the end of the year; or
your taxable compensation for the year.
(Taxable compensation is generally wages that you worked for - W-2 or net self-employed income minus the deducible part of the SE tax, but can include commissions, certain alimony and separate maintenance, and nontaxable combat pay ).
See IRS Pub 590A "What is compensation" for details:
https://www.irs.gov/publications/p590a#en_US_2018_publink1000230355
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
