These two images are typical rural sprawl compared with Central Manhattan, on the exact same scale. Now I'm not an expert on these matters, but something tells me pollution, traffic and logistical problems would be much, much worse is everyone had their own plot of land.
Thats a good ass start tbh. I started on conservation work and moved to small scale organic agriculture. Biggest lessons I've learned is to work with and not against your natural environment and treat your whole operation holistically. Everything is interconnected and any tweak needs to consider every other input. Start small, learn what works, and seasons after season add one more operation. And honestly eat what grows easily, instead of killing yourself trying to grow what you think you want to eat. In the face of climate collapse we're all going to be eating whatever we can manage honestly