Presidents only sign or veto legislation passed by congress.
When the president was Republican and the congress was democrat, as in the 1980’s tax receipts as a percentage of gdp went down. When the president was Democrat and the congress was Republican, the opposite happened.
That’s not projection. That’s on the chart you posted.
That's simply not true. The largest tax cut in the history of this nation was PROPOSED by President Reagan. It then was originated and passed in the Democrat controlled House because of his leadership on the issue. A good president can do a lot more than just sign legislation.