The Standard Deduction for individuals that can be claimed as a dependent is the lesser of (1) $12,000 or (2) the greater of $1,050 or $350 plus the individuals earned income. So yes, if all the income is unearned, the amount over $1,050 is taxed using the "kiddie" tax tables.
The new law retains the computation of "net unearned income" (NUI) as a
key element in determining the new kiddie tax. NUI is the excess of a
child's unearned income over the sum of (1) $1,050, plus (2) the greater
of $1,050 or the child's itemized deductions related to the unearned
income.
So the amount above $2,100 is taxable.
For details on all the changes, see the following Journal of Accountancy article: https://www.journalofaccountancy.com/issues/2018/nov/irs-new-kiddie-tax.html
[Edited 03-26-19]
