What powers do the president and Congress have to enforce their policies and laws?

The US Constitution gives the legislative branch of the federal government (i.e., Congress) the primary power to make the nation’s laws. The executive branch, which is headed up by the president, is primarily responsible for enforcing or carrying out those laws.
In addition to the president, who is both head of state and commander in chief of the armed forces, the executive branch includes the vice president, the Cabinet, 15 executive departments (Agriculture, Commerce, Defense, Education, Energy, Health and Human Services, Homeland Security, Housing and Urban Development, Interior, Justice, Labor, State, Transportation, Treasury, and Veteran’s Affairs), and various independent federal agencies (including the Environmental Protection Agency, Social Security Administration, and Securities and Exchange Commission).
The president can sign or veto legislation passed by Congress but can also exert influence and enforce the nation’s laws through executive actions, which include executive orders, proclamations, and presidential memoranda. The departments and agencies that belong to the executive branch are responsible for carrying out the regular enforcement and administration of federal laws and executive actions. Each is led by a department head, chosen by the president and confirmed by the US Senate, and given a specific budget each year to enforce federal laws.
https://www.usa.gov/branches-of-government

https://www.whitehouse.gov/about-the-white-house/the-executive-branch/