Convert 3D view into 2D

Question:

Hi there, I am trying to build a kitchen planner | room planner. I am working on three.js library and I am trying to replicate this project IKEA Room Planner for experience. The issue is that I don’t know what to use and where. Like in what framework, library or language should the 2D part be made and how to convert it into three.js.

Expectation:

To be clear I don’t want a whole code just an idea or a way of performing the action.

[EDIT] 2D to 3D will also work!