You cannot open the chest, which is on a raised wooden platform until you have dealt with all the surrounding hilichurls, so take care of them first.
Navigating to their playlists or the search bar will be your best bet if you cannot find said content.
Mondstadt Grilled Fish Ingredients: Fish x1, Pepper x1 Location: Unlocked by Default Effect: Revives the selected character, restoring 50-150 HP.