I think that the issue of increasing and decreasing the scope of government might be contingent on the particular individual that interprets the role of the office. For example, President Franklin Roosevelt believed that the office of the President could be used to assert greater influence that the government had in the lives of its citizens, as represented by passage of New Deal initiatives. By the same token, President Reagan was one that believed that the President's function was to minimize the role of government in the lives of its citizens. The scope of government, as a branch, has changed in an massive manner since the time of the Framers. Simply put, the Presidency refers to so very much like a Chief of Staff, Press Officer, and issues related to Civil Service that have made "the executive branch" the largest in terms of scope and personnel size:
One of the radical changes in government since Washington’s day has been its enormous increase in size and complexity. Civil service, once welcomed as a reform of the spoils system, has in fact created a nightmare, effectively a fourth branch of government, known as the bureaucracy, which is not responsible to an electorate. The regulatory function of government, which the bureaucracy controls, has expanded enormously. From 175 bureaus and agencies in 1923, there were 767 in 1992. By 1991, the Code of Federal Regulations consisted of nearly 200 volumes and more than 100,000 pages. One of the central tasks of the twentieth century president has been managing the massive bureaucracy that controls these regulations. Nixon’s response was to surround himself with a counterbureaucracy in the White House of some 4,000 staffers.
In assessing the scope of the executive branch of government, I think that the perceptions and reality of the branch have to be taken into account when examining its role on the scope of government.