Realistically, what can Dems do to stop/slow Trump and Elon’s unraveling of the federal government?

As Trump and Elon continue to dismantle government agencies and push the limits of what they can do, I've seen a lot of liberals and progressives express frustration at Democrats in congress for not doing more to stop it. I'm starting to share that frustration, but I don't know enough about the federal government to have an idea of what they can do. Beyond "doing more", what specific actions can they take that have a decent chance of succeeding?