Subdividing/smoothing (rounding) an already animated/rigged 3d model?

Hi there!

Does anyone know of any tool/technique/assets (I only found like 1-2 that subdivide the polygon count (and smoothing/rounding (like meshsmooth/turbosmooth/opensubdivision (catmull-clark subdiv)) an already rigged/animated model (like say a bought character human/animated asset with the rig/animation and everything already made);

-So far found that you could transfer the 'vertex weights' to another model (one that would have more resolution and would keep the skinned mesh animated vertex data)...there is 1-2 assets that transfer vertex skinning...to another model..(skin/animation data remapping to new model that is just the low model but subdivided in polygon count)

-Using meshsmooth/subdivision in Blender - it destroys the vertex data from the lower-res animated model...

-Using a smooth/relaxing modifier (that rounds the model..but does not add any polygon subdivision...)

-At the least, just any rounding/smoothing script/tool that 'softens/relaxes/rounds' the hard edges/3d shape?

Thank you for any help.