After trying to read and apply all the suggestions by Reallusion and this community I'm still at a loss. I've used the Hirewire Huntress model in CC3. No changes. Then exported it to an FBX for Unity3D using all the "correct" settings. I've not used LODs nor changed the texture Max Size (default greyed out). Then created a fresh HDRP project in Unity (2019.4) and imported the latest Auto Import package from Reallusion. The import works great. Apart from some metallic or smoothness tweaking and some trial-and-error getting the hair looking nicer, it works like a charm.
My issue is with the clothing. When looking at the Jacket there is clear tesselation visible (see the arm in the screen shot). The mesh looks very coarse and not at all like it looks in CC3. When I try the HDRP/LitTesselated shader and tweak the tesselation options nothing seems to happen. Is this because the clothing is using a Skinned Renderer?
The bottom line question is: how to get the clothing looking smooth?