That isn't how statistics work. Sample size reduces your error relative to the population you are randomly sampling from.

When you don't have a random sampling, then you sampling method is what determines how generalizable your findings are. A good sample size with a bad sampling method tells us little to nothing about the general population and only informs us about the specific sub population for which the sample can be considered a random selection from.

With significant differences in voting rates across many different demographics, votes are absolutely not a representative sample of the overall population.