I'm confused. What has first touch to do with size? The likes of Ibrahimovic and Berbatov have very good first touches. So did Zidane. And Bergkamp was the master of it.
Obviously there are some technically skilled tall players. Even then Zlatan's first touch was hit n miss at Barca. Most big sized targetmen have an inconsistent first touch, that relies a lot on confidence and form. They take a while to get going. It's what i've noticed but i could well be wrong.