To be fair, Clinton won the popular vote by a large margin, it's just that the House has not been expanded in 100 years despite the population more than tripling, so some states have outsized impact during a presidential election.
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.
Congressional districts are divided among states based on the census, and then become the count of electoral votes, which in turn award the presidency. So they have a lot to do with presidential elections.
But you wouldn't just double it for each state. You'd increase the total number of House seats, and then portion them out according to the populations of each state. That's how it was always done before they capped the size of the House.
Currently, Wyoming has just one House seat. If you double the number of total House seats, Wyoming still only gets one. They currently have a larger impact on Presidential elections than they should if it were decided strictly by population, and that's due entirely to the Electoral College and the cap on the size of the House.
The size of the electoral college is based on the size of the House, because the House (currently) has a fixed size, the states each get a set number of electoral votes, that do not actually match the populations of those states.
This is due to a law passed in 1929 called the permanent apportionment act, which froze the size of the House, despite the fact that we've added two new states since then.
So States like California have less electoral power than they should, while states like Rhode Island have more than they should. Well, technically Rhode Island should have more as well, every state should have more.