I don't think it requires a plugin, but you can go to Settings >> Hotkeys and search for "fold" to create/change custom hotkey settings to fold up/down as necessary.

Another approach with a potentially similar affordance: Obsidian has a core plugin called "Outline" that you can enable. Then open the palette to search/select: "Outline: Show Outline" which will display in a sidebar (you can drag/drop it where you find most convenient). This side outline will allow you to easily jump around your document for various views as well as show you the overarching outline while you're working on a document. It will also allow you to conveniently collapse parts of the outline too.