For Trump or Harris to be President, either of them is required to get a minimum of 270 Electoral College Votes. Out of the total 538.

Each State is allocated a certain number of electoral college votes based on size of its congressional delegation.
This includes the number of Senators and Representatives that each State has , plus 3 congressional votes from Washington DC.

The 538 Electoral College Votes are derived from 100 Senators, 435 Representatives (Members of the National Assembly), and 3 votes for DC..

In majority of the States, the winner of the popular votes carry the total allocated Electoral College Votes.

For example, looking at the 7 Swing States, i.e.; Pennsylvania has 19 Electoral College Votes. North Carolina 16. Georgia16. Arizona 11. Wisconsin has 10. Nevada 6. Michigan has 15 .
In each of them, if you win in the popular votes in, let’s say, Michigan, you will have won all the 15 Electoral College Votes therefrom.

The 7 aforesaid Swing States decides who will become President of the United States. Combined they have 93 Electoral College Votes.