Is the largest state in the US soveregin because of its population?

No. Alaska is the largest US state by area, and is not its own sovereign nation. California is the largest state by population, but it too is not its own sovereign nation. However it would be possible FOR California to be its own sovereign nation, because of its massive economy and population (california has the 8th largest economy in the world, about US$1.6 trillion, and the 34th largest population in the world)