Trickle Down Economics is a meme from the Left that has no bearing on any of the Reagan administration's policies. It's a dumb idea, spouted by people with a really, really bad preference when it comes to economic policy and it had nothing to do with the realities behind the Reagan boom.

You can read an essay by an economics genius on this very lie, for free, here:

https://www.hoover.org/sites/default/files/uploads/documents/Sowell_TrickleDown_FINAL.pdf