The world ALREADY produces enough food, potable fresh water, and vital consumer goods to sustain the entire world’s population in quite literally utopian abundance. The only reason this is not the case is due to capitalism’s design of suppressing the working class and periphery. In fact, in a socialist world, you would most likely be able to feed even more people with significantly less land; since a socialist planned economy will not careen itself growing wasteful, space hogging, and high water consuming plants like almonds for example.

For example, enormous quantities of food are purposefully destroyed, ruined, or left to rot simply to maintain a high market cost and profit. It is also not profitable to distribute food and goods to certain areas, populations, or regions, so capitalist will simply avoid them, leaving the people there to suffer.

As for space, there is more then enough space in the world for 8 billion, and much much more then that. The extremely high density and vertical construction of Chinese and other Asian cities stands as a testament to that.