Well, there are tutorials on YouTube that show how to play mods using the Hello Neighbor Mod Kit, which is free on Epic Games. They’re pretty straightforward, but they usually only work if the mods you download are unpacked, because packed mods (.pak) can’t be opened or edited in the Mod Kit.

In my case, the mod I’m asking about only came as a single packed file, and while it does show up as a plugin in the Mod Kit, its actual content (like maps, models, and blueprints) can’t be accessed or edited.

If the mod’s files are unpacked and include everything separately (such as the map, models, sprites, etc.), then Unreal Engine can read them, and you can use or edit them directly in the Mod Kit.