The software I use is a Japanese software called Metasequoia, similar to Blender modeling.
I often create them by extruding from a basic shape box.
I load the modeled clothes into VAM, pose them, check them, and repeat the process of fixing the broken parts, and finally set shims on the parts that can't be helped.
I don't know much about the technical details, so I will give you the OBJ file at a later date so you can take a look at it.
I love the necklace you created. The dress is also very artistic and amazing!