Matt talked about signing statements.
The American Presidency Project tracks signing statements from Hoover through Obama, as well as executive orders back to 1826 (Ironically, or not, the year Jefferson died. His was one of the most eloquent voices cautioning against such power in the executive.)
I’d also like to add a plug for David Gray Adler, one of the most articulate presenters on presidential power I have ever heard. A recent article is here: Executive power is ‘pregnant with menace’