Banishers: Ghosts of New Eden has a very similar level structure to the 2018 God of War reboot, in that while it is technically an open world game, it's more of a Metroidvania. This means exploration is mostly through interconnected levels with branching paths, but there's usually only one route forward. From almost the very beginning of the game, you'll encounter paths blocked by destructible rocks that you seemingly can't get rid of. Here's what you need to know about breaking these rocks in Banishers.
How to break destructible walls in Banishers
The short but sweet answer is that you need to use Antea's Outburst ability to clear the rocks. These destructible walls are only blocking optional paths to begin with, so you don't need to fret about missing anything important, as you can backtrack later down the line because Outburst isn't available to you from the get-go. Antea's abilities are unlocked gradually throughout the story.
Outburst is unlocked during the quest Old Acquaintances when your objective is to simply "reach New Eden Town." You'll have a sub-objective to rest at shelter, at which point Red and Antea will discuss the events so far, including Kate and Deborah. For me, this occurred at the Mossy Watchtower campfire, which is in the swamp environment, shortly before the old fort. It took around eight hours, give or take, to reach this point.