This is very good. In my opinion, biggest problem here is wide flat surface. It makes those mountains to look like big rocks, and automatically colossus and horseman looks a lot smaller. Also it looks like they aren't very far away from each other, and that makes colossus smaller. Maybe you should try to change perspective and find better angle for this composition. Here are some useful links related to this topic -> [link][link][link][link] I hope that this was helpful.