At this point I think it's been spoiled, so I'll say that's also just one of a few that'll be placed in the attraction. The Chamber of Secrets as seen in the films features dozens of those serpent heads, so here's a bit of size comparison:
That figure in the distance is Harry at about 4 feet or so. That gives you an idea about the size of the actual serpent heads, which are also partially submerged underwater.