Shirt mannequin wearing plaid Low-poly 3D model is available on CGTrader for $5. Original author: pirinatoda. Specs: 36085 polys, 20177 verts.
STL (Stereolithography, filesize: 631 KB), OBJ (OBJ, filesize: 1.74 MB), BLEND (Blender, filesize: 864 KB), GLTF (glTF, filesize: 1.42 MB), FBX (Autodesk FBX, filesize: 1.92 MB), ZPAC (Marvelous Designer, filesize: 7.16 MB)