Edited
Very little till he 'created' out of thin air(Digital Services) the new powers & policies of DOGE.
And he is freezing past allocated funds by congress, which in many ways is very illegal.
And he is firing large swaths of governmental officials and whole departments. That is the responsibility of Congress and department heads in those agencies. He has not been given that power, but he took it because we have not stopped him. He has stepped around regulations just enough that it is not outright absolutely illegal, and can stay in the courts for a long time before it gets to the supreme court.
These powers have been intentionally given to congress as a body of elected officials, rather than to the executive branch. That was to guard against a Dictatorship. That's why the US Congress is the only body allowed to create a Department in the US government, because it is a body, and not an individual. But Trump tiptoed through the Tulips in combat boots when he added to the name of an already existing department, and illegally added responsibilities that had nothing to do with the reason for it's original creation.