Roman Combat Helmet (Polygon mesh 3D model) is available on CGTrader for $5. Original author: Blender-Arcturus. Specs: 238592 polys, 279645 verts.
OBJ (OBJ, filesize: 106 MB), FBX (Autodesk FBX, filesize: 56.3 MB), BLEND (Blender, filesize: 3.76 MB), TEXTURES (Textures, filesize: 98.6 MB), GLTF (glTF, filesize: 127 MB)