If you increase the members of congress, then that's going to increase the number of electoral college votes needed to win as well. So, proportionally, it all stays the same.
They wouldn't though, the people in charge of changing this would not allow states like California and New York to dominate the process, which they would if it were based purely on population.
The problem is the people proposing the change and the people in charge of implementing the change are two different groups of people. ;)
You think, for a minute, the people responsible for blocking Merrick Garland from getting a Supreme Court hearing, are going to give states like California even an inch more power in Presidential elections, well... you have a greater faith in humanity than I do.
The only reason they haven't changed the congressional makeup is because they haven't (yet) figured out how to empower low population red states at the expense of high population blue states.