This is a kitbash of clothes. There are 168 possibilities to make T-shirts with different collars, sleeves, and bottoms.(1blouse*7collars*8sleeves*3bottoms)
There are 19 parts of T-shirts that you can combine. The product contains an upper-body wear called Blouse, 3 bottoms, 7 collars, and 8 sleeves. All parts are remeshed and vertices in borders are matched and can simply weld. So you choose the collar, sleeve, and bottom you want, then weld the vertices at the borders between them to make the final mesh. The video shows you how it works in 3ds max, but you can do the same process in Maya, ZBrush, Blender, C4d, etc. You can download the video for free and see what you can do.
In Marvelous Designer you should simply sew the parts together.
All meshes are mid-poly. To get smoother mesh just use subdivide, turbo smooth, etc.
All models were created and remeshed in Marvelous Designer.
File format in quad mesh: .obj, .fbx, .max, .ztl
File format in triangle mesh: .zprj
UV maps are packed in Rizom UV.
Rendered by Marmoset toolbag 4.