Hi there,
Technically speaking, all Lyra experiences (a.k.a. game modes) are, in fact, custom “game features plugins”, which are indeed part of the official UE’s “plug’n play” design approach, alongside Modular Gameplay. If you are new to UE, it’s a good practice to develop your game with modular features, using actor components, plugins and game features plugins, so you can “turn features on and off” as you see fit.
Best of luck.