Biden is making it a rule that all government vehicles should be electric from now on. Given that across the country the government owns hundreds of thousands of cars and other vehicles, and this change alone will reduce global emissions by several tonnes per vehicle each year. More to the point, this requirement would guarantee significant income for electric vehicle made that could meet requirements. How many of these, would be supplied by Tesla would be interesting, however it still something that would encourage other manufacturers to work harder on filling this space.
Biden has also made it clear that in the future all new power generation should be clean. At the current time, they are already moving in this direction. At the moment 84% of new power is clean, as such a decision from the president could be the push it needs.
In the USA there are over one million unused oil and or gas wells. These leak huge amounts of methane, as well as being a significant risk both of fire and explosion. Given the current significant problem with global warming from greenhouse gases, and the fact that Methane is even more powerful a warming gas, capping these wells is essential. Of course if america had sensible climate rules, each of these wells would have been capped by the drillers as they went.
Finally, Biden has said that the USA government is going to move towards eradicating all oil and gas subsidies. Currently, the USA government spends a significant amount, often thought to be around 40 billion dollars a year (a quick search gives you figures from 20 billion, to over 100 billion). This amount is huge, and by sensibly investing it, it could rapidly change the finances of low carbon industries.