"Wrl models are meshes and they can be open surfaces or manifold
(closed volume) surfaces. STEP models are solids, closed objects
and they have geometrically precise surfaces which can be curved,
meshes can't. There's no direct conversion between the two formats.
It can be done, but there's no "batch conversion" tool to do it
automatically. The closest thing to automation would be to use Part
WB to "Make shape from mesh" and then "Make solid from shape",
which will work if the mesh is a clean manifold, and the solid could be exported as .stp, but intensively manual. Fusion has T-splines conversion from facet objects to nurbs surfaces, but that's Autodesk proprietary stuff..."
https://forum.freecad.org/viewtopic.php