The last time we downsized government legally was in the 1990's through the "Re-Inventing Government Program" led by VP Al Gore. The purpose of this program was to make the federal government work better, cost less, and get results that Americans care about. The program execution took more than six years and was done in conjunction with congress, i.e. basically congress was asked to make the required changes to laws and regulations to permit the proposed changes. The results of this program were: the size of the federal workforce was reduced by about 350,000 people and common sense changes were made in the way government works that saved taxpayers $137 billion (BTW - the program didn't result in the kind of chaos and confusion that is happening now).
It would have been nice for Trump and Musk to do their homework on how to make the proposed changes to our government without creating a constitutional mess but that would have taken a little forethought, planning, and working with congress which I think is way over the head of these bozos.