Where is a 3D game engine with a programming model based on behaviors and events like gdevelop?
I do not know GDevelop. But this is a forum about Castle Game Engine and we have events and behaviors (TCastleBehavior) and much much more 
Feel free to explore the engine and ask questions, you can start with intro video on Getting Started | Castle Game Engine .
We have in examples various games, 3D and 2D, platformer (examples/platformer/), strategy game with isometric view and other (examples/tiled/strategy_game/).
We support many platforms – desktop, mobile, consoles (Switch). More features are listed on Features | Castle Game Engine .
Castle Game Engine follows a more traditional way of creating games with the help of Scene / UI editor. So I am afraid it won’t fit your need in it’s current state, as right now it requires you to code game logic instead of using event sheets (or any form of visual programming) like GDevelop. So maybe GDevelop’s variants, like Clickteam Fusion or Construct may fit you better.