pf2e.fyi
From Pathfinder Gamemastery Guide, which isn't enabled.

Fortify Camp

ACTION

You can spend time fortifying your camp for defense with a successful Crafting check (typically at a trained or expert DC). Anyone keeping watch or defending the camp gains a +2 circumstance bonus to initiative rolls and Perception checks to Seek creatures attempting to sneak up on the camp.

Pathfinder Gamemastery GuideOGL