How do you unlock more housing plots?

There is no shop or currency that buys extra plots: you get them by pushing the Homeland and the RV forward. Additional homeland areas open the same way, so expanding your space is a side effect of levelling rather than a separate task.

The RV is the upgrade most directly tied to land. Upgrading it raises the number of farming plots you can use, and you need it to advance your farmland level. The catch is the gate in front of each RV upgrade: every woodland plot you already have must be placed first, which means six at level six. If an upgrade will not go through, check for an unplaced woodland plot before anything else.

Homeland level-ups pay out alongside the extra space. They grant modification kits, cosmetics, extra health and access to crafting systems, and a higher Homeland level also opens a personal incubator for hatching eggs. Levelling for plots and levelling for those rewards are the same job.

Not settled: No single Homeland or RV level is fixed as the point where each new housing plot opens. Progression unlocks them, but the step that releases each one is not pinned down.