Here's how the Trump economy works: Trump weighs big tax cut for rich: report - THE HILL. Note, this is intended to be a unilateral gift, not going through Congress.
Treasury Secretary Steven Mnuchin at a recent G-20 meeting in Argentina said if the tax cut can't be done through Congress, the administration will "look at what tools" are necessary to consider the move.

"If it can't get done through a legislation process, we will look at what tools at Treasury we have to do it on our own and we'll consider that," Mnuchin said. "We are studying that internally, and we are also studying the economic costs and the impact on growth."
The problem, of course, is that it has already been studied: Indexing Capital Gains to Inflation - the Wharton School.
Our analysis suggests that this policy would cost $102 billion dollars over the next decade. While high-income households would benefit most, the share of taxes paid by AGI would not change meaningfully.