Design patterns for Game engines

I was wondering if there exists alternative Design Patterns for Game Engines (Unity, Unreal, etc)

To be short: I was implementing a mediator, and, although the main purpose: "have a group of UI elements interact in a unique place" persists, and is really super useful, the Open/Close principle, and the re usability of the UI code gets really faded through the "already-made" buttons, Inputs, etc, and the expected use of them.

Glad to know your opinion!