Set the size of the gltf obj

Hello, my first post here!!
Recently started working with three js and models from blender.
In blender i made some models, and gave them the size in cm .
I’m making some sort of 3d furniture modeling, and want to be able to work in dat.GUI with the size not the scale so that 0.9 corresponds to 90 cm . I can see the measurements i gave to my model through>
var bbox = new THREE.Box3().setFromObject(gltf.scene);
but i have no idea how to set it. Maybe there is a simple solution like obj.scale.x = 1 but with size.