Civilian bureaucrats - in fact pretty much all discretionary spending - are line noise in the federal budget.
By far the largest components of spending are Medicare, Medicaid, Social Security, and defence.
Cutting social security means that old people get less money in their retirement, no ifs, ands or buts. Good luck with that one.
By American standards, Medicaid and Medicare are pretty efficient. So any cuts are going to mean that either doctors get paid less or fewer health services are provided. Yes, politically, Republicans can get away with cutting Medicaid, but it’s the much smaller piece of the pie compared to Medicare. Good luck with either one of the options above with Medicare.
As for defence, procurement is a giant money tree for defence contractors, but a large part of the reason why it remains a giant money tree for contractors is that they build plants in every single congressional district there is, so trying to apply some sanity to the defence procurement process is politically untenable. Beyond that, are you going to be the one to tell the Marines they don’t need their own aircraft carriers?
Of course, tanking the American economy by removing a significant chunk of its labor force (undocumented immigrants) and increasing costs (by putting tariffs on things) is just going to make the problem harder by crunching revenue.
The right of politics has forever claimed that they can painlessly cut taxes, and it’s always nonsense.