There are a few different ways of thinking about this problem. As per this previous answer on scaling for AR the default size of a cube in Unity is 1 square meter.
Also the default starting position in STYLY is (X:0, Y:1.3, Z-5), this of course can be moved in the studio.
I find it helps to create a stand in object which approximates the scale and position of the users default starting position and height. To do this I add a cube to my Unity scene, I then give it the following scale and position values
Position: X:0 Y: 0.9 Z:-5.1
Scale: X:0.5 Y:1.6 Z:0.3
This will give you a pretty good idea of the scale of a person in your Unity scene and also the default starting position.
I'm designing a scene for STYLY VR in Unity but I'm having trouble getting the scale and positioning correct. This can be problematic because you cant reposition or scale scenes once they're uploaded onto the studio. Does anyone have any tricks to help with this problem?