Judging by the mesh resolution, maybe 1200 tri's at best, looking at how the elbow bends in the first promo image, the elbow topology is not professional (or severely limited by linear interpolation), I'm guessing they may have modeled it themselves, or the character was made for mobile game or for a sim like game. If you are looking for a character with several morph targets, I can't say I know of any characters that come with morphs. I know I've seen a few before, but its not common enough that its an asset I would see on the unity store or on more professional sites like turbosquid. Adding morphs isn't hard, but maybe getting the right size and morphs would be.
What you probably want to look into is looking into 3D models with topology you like, no more than 1800 or 2400 tri resolution, and probably pre rigged as an FBX. The higher the resolution the more of a pain it will be to sculpt and make morphs for. However what will probably harder, even if you do find a character with morphs, is getting animations working in game. In general I've always found it a pain. Unless there is such an asset already working in unity with morphs, you may want to look at 'non idea' characters or models just to see how they get the shape morphs working. Last I checked, in order to get morphs to work, assuming you weren't just layering animations, but actually using shape morphs, was to back your morphs into an animation (in a 3D modeling program like Blender), and then control that animation with a bone that you can then animate, and then in unity you can control that second animation to actually get the morph working effect. its overall a technical hassle. Their may be a model set up, but in my experience finding something 'functional' while very hard is often only 'the bare minimum' and the things I end up wanting to do ends up being easier if I start from scratch... even if that means I have to learn how to do something. Sorry I can't be of much help.
