Galeano, in the introduction to his Open veins of latin america, states that the only reason south america isn't as densely populated as Europe, is intentional underdevelopment, and colonialism. The European powers intentionally depopulated the indigenous of many of these countries by turning their economies into mono-crop / mono-mineral mercantile export ones from the 1500s onward.

I'm sure someone has tried to figure out earth's carrying capacity, but we're not even remotely close to it. There isn't even any vital resource whose production doesn't scale with population growth.

The fear-mongering about population growth is really only coming from euro-amerikkkan capitalists and white supremacists like Bill gates, who are mirroring their 1800s counterparts with population control attempts in places like Africa. Bill Gates openly says he's trying to stop "population increase in places we don't want it", showing his fear of the growth of potentially threatening non-white populations.