Check out Architectural Linear Stairs with Handrail 3D model on CGTrader for $22. High-quality mesh by modernarchstudio.
STL (Stereolithography, filesize: 13.8 MB), OBJ (OBJ, filesize: 3.56 MB), FBX (Autodesk FBX, filesize: 1.22 MB), DWG (AutoCAD, filesize: 663 KB), 3DS (3D Studio, filesize: 1.55 MB), DXF (DXF, filesize: 1.66 MB), DAE (Collada, filesize: 1.94 MB), STP (STEP, filesize: 4.63 MB), 3DM (Rhinoceros 3D, filesize: 2.21 MB)