If you just want that, run your game with the lit buffer, it’s more simple and you have nothing to change in your materials or/and your lights.
Plus, I don’t really like the method of the emissive for that kind of effect, the third solution is to add a Skylight set in movable and disable “Casts Shadows”, all your level will be lighted the same way and if you don’t like the AO you just have to put a post process volum and disable it.
The advantage of this method is that you can still have your “lit” effect and add “next gen” effect if you need to, you’re not stuck with the lit buffer nor emissive materials. Artistically it’s better in everything :).