From this page of the guide to Returnal you will learn how to open the stones that bar access to containers with items.
The planet Atropos in the game Returnal is a very treacherous place, where you should expect many a danger, but also lots of hidden locations, underground crypts with sarcophagi, and alien devices, as well as sealed rooms with objects.
During exploration, you may encounter containers or objects that have been hidden behind solid stone bars. This obstacle cannot be overcome with firearms or melee weapons.
There is always a distinctive switch with a blinking yellow-red light near the grating room, which must be located and then shot to activate the gate opening mechanism.