A president's first term tends to follow a particular pattern: bold action at the very beginning to see what they can get through Congress. They focus on things that will improve their chances to be re-elected. Biden likes to cite the Inflation Reduction Act and it's policies and some others.
Toward the end of their first term, they start looking forward to our year long election season. There's less policy implementation and more campaign promises.
Assuming they get re-elected, they can't be president for a third term so why not go bigger than the beginning of thy first term? Now they can get to work with worrying about the political consequences because there are none for them. And the greater their accomplishments in their second term, the better their party looks.
In short, political incentives differ between terms, with term limits making bolder action more desirable and likely.