It’s hard to predict this in advance, since it’s sensitive to things like voter turnout in non-competitive states. For instance, a blizzard in New England could affect the popular vote without impacting the electoral college vote. So I’ll just tell you how to calculate it.
First, identify the tipping point state. Some guys think it might be Michigan this year. Meaning either candidate can win by winning Michigan and every state more favorable to them than Michigan. Other good guesses are Pennsylvania and maybe Arizona. Then take the difference between a candidate’s margin in Michigan verses their national average.
2020: The tipping point state was Wisconsin. Biden won WI by 0.6% and nationally by 4.5% representing a 3.9% electoral college advantage to the Republican.
2012: The tipping point state was Colorado. Obama won CO by 5.4% and nationally by 3.9% representing a 1.5% electoral college advantage to the Democrat.
So the electoral college doesn’t intrinsically benefit the Republicans, but it probably will this year.