I looks like a basic plastic shader to me, but with some subsurface scattering.
You could also try instead mixing (never add) translucancy, but that gives the idea that the mesh is hollow , as far as I experienced.
I’ve seen some theories about the subsurface scatter, but for me it works as follows; Open the subsurf in the principled shader completely. More important is to adjust the radius. Give them all the same value (unless you want to give the scattering a color). The higher the radius, the more scatter, or the softer the material looks. For regular sized objects, I use often 0.2 , but it depends how thick your mesh is. Subsurf doesn’t make the object/mesh look like hollow, in contrast to translucancy.
So if you go for thin plastic use translucancy.
The heart looks a bit hollow to me, not sure about it though.