Two unfortunate circumstances can occur rather quickly in Starfield: inventory encumbrance and a simultaneous dwindling supply of necessities. As players explore Starfield's massive world, they will find more loot than they can manage, and it will typically come at the cost of using necessary items like ammo and medical supplies that are a bit more difficult to find. As such, in order to stay in control of their inventory, players will need plenty of vendors to buy and sell to.
Source：https://www.cbr.com/starfield-vendor-guide/
