In what 3 ways have former presidents expanded the power of their office?

One way is what Jefferson did with Louisiana purchase. He purchased the land for the United States without congressional approval which was odd at the time and questioned by many but was not illegal or unconstitutional so it was kind of established that the United States president has the power to do so if they desire.

Another is that Lincoln raised an army without congressional approval. It is generally understood due to the constitution that only the congress may raise an army for various needs and then the president as chief commands it, but Lincoln raised an army without congressional approval because of dire needs of the civil war.

Third is how Franklin Delano Roosevelt expanded the role of the president in the federal government. The president was more or less just an executive person who did what the congress told him to do, but FDR managed to increase the power and implement numerous things like laws and programs through this increase of power.