How to add viewports with another scenes?

Phaser 3
1

For example, a 800x600 game, on a 2D UI Scene, I want to add a viewport from the position 200x100 to 400x250 with a 3D Scene. I am capable with Godot Engine.

2

https://newdocs.phaser.io/docs/3.55.2/Phaser.GameObjects.Extern