Make a scene continue running in background

Is there a way to make a scene run background while another one is active so I can interact by code with the first scene? Thanks.

Technically, only one scene can be active at a time (see what that means here)… but I think by “active” you mean loaded. Additive scene loading should do the trick for what you want to achieve: if you additively load a scene, the game objects of that scene will also be present, rendered, updated, physics applied, etc.