Outposts in State of Decay are important for a variety of reasons. Depending on the building you make into an Outpost, you can have a variety of bonuses, including daily resources, water or electric utility in your base, or in some cases, military call-ins like airdrops. After recent updates to the game, you can get even more out of some Outposts you have claimed if you have the resources. Here is how to upgrade Outposts in State of Decay 2.
There are two ways to upgrade an Outpost in State of Decay 2. The first way is within the Outpost itself after you claim it. Go to the command post for the Outpost and select Open Outpost. You will have two choices between upgrading and abandoning the Outpost. Read over the benefits you get from the upgrade before spending for it and click the button. The upgrade should take between 40 and 60 seconds.
You do not actually need to be in the Outpost to upgrade it. As long as you have the resources, pull up your map and tab over to Base. On the right-hand side will be the Outposts you have claimed. Click on the Outpost you are interested in upgrading, and you can begin it right here.