Just looked at Wikipedia and this is all it says
by the executive order of President John F. Kennedy, w
Says no more about any congressional action. The Foreign Assistance Act they did.
en.wikipedia.org
Creation
Congress passed the
Foreign Assistance Act on September 4, 1961, which reorganized U.S. foreign assistance programs and mandated the creation of an agency to administer economic aid. USAID was subsequently established
by the executive order of President John F. Kennedy, who sought to unite several existing foreign assistance organizations and programs under one agency.
[8] USAID became the first U.S. foreign assistance organization whose primary focus was long-term socioeconomic development.
Congress authorizes USAID's programs in the
Foreign Assistance Act,
[9] which Congress supplements through directions in annual funding appropriation acts and other legislation. As an official component of U.S. foreign policy, USAID operates subject to the guidance of the
president,
secretary of state, and the
National Security Council.
[10]