If we can ignore “checks and balances” for real,

Step 0: declare the US constitution mostly void, to prevent stupid hacks like “states rights” or “fed can only regulate interstate commerce” or whatever. Keep its remnants around to ensure institutional knowledge and capabilities are preserved, until a transition to better institutions is implemented. Declare all capitalist parties illegal, seizing their assets. Then move on to the plan:

1. Immediately nationalize all rented-out residential buildings and set up social housing. Introduce a hard limit of two residential units per person. Prohibit commercial entities from owning residential properties.
2. Immediately nationalize all healthcare and pharmaceutical organizations
3. Immediately nationalize all organizations of national importance (high number of employees, monopolies, military-adjacent)
4. Require all other businesses to be turned over to employees, co-op style, within a certain timeframe (this is to allow for graceful handover at least from those small business owners who cooperate). Modify tax codes accordingly
5. Require a merit-based entry system into universities and colleges, forcing all higher education to be free. The deciding factor of which university you attend is your exam scores. Set up funding for the institutions appropriately.
6. Everyone with over a billion dollars in assets (before the previous steps) get their property confiscated, goes to jail, and has to work at minimum wage until they repay what they have stolen from the people. Those who repent and collaborate may be released earlier under certain conditions, like a hard limit on earnings and restrictions on travel.
7. Introduce a plan to transition away from animal agriculture, with a set timeframe to completely prohibit animal-based foods and other unnecessary animal suffering
8. Introduce a plan to transition all densely populated areas away from car transportation, with a set timeframe to completely prohibit private vehicles in all cities
9. Introduce a plan to transition from fossil fuel use to sustainable energy sources, with set timeframes for net-0 and complete elimination of fossil fuel use. Limit use of oil derivatives, with a plan to reduce them to minimum necessary (such as medical uses)
10. Prohibit all organized religion. Make proselytizing a crime similar to fraud. Mandate all education be based on materialism (and therefore atheism)
11. Allow formation of various socialist or communist parties. Require free, competitive, ranked-choice elections for all positions within parties. Require ranked-choice voting for all positions in the Senate. Require proportional representation for House elections. Introduce a plan to replace POTUS with an executive committee, with halves of the committee elected in a staggered way via proportional representation to ensure both continuous, stable leadership and adequate representation of new ideas. Introduce a plan to reform the judiciary with significantly more checks on the supreme court. Require similar election schemes for state&local legislatures and executives.
12. Immediate pardons for persons imprisoned for anti-capitalist viewpoints or actions, drug possession or consumption (maybe some others too)
13. Help socialist, communist or otherwise leftist movements worldwide, but especially in the Americas. Aim towards a pan-american union of socialist republics with freedom of movement, free trade, resource sharing and other collaboration
14. Introduce a requirement for 50% of all positions within a certain level of parties and government to be filled by women. Enshrine abortion and LGBT rights into law. Introduce a long-term plan to eliminate the concept of gender from society
15. Introduce a long-term plan for the state to wither away and transition to communism, whether it is commune-based anarchism or collectivism

If we manage to push through all these changes, I wouldn’t want to be reelected for any amount of terms.