I'm building this using Command Block. And surprisingly, it's easy. I can't believe it. So I shared to you guys how to build this. I also build Colossal Titan using command block either and I make a Rumbling! Which is pretty interesting to my world and my friend's server. By the way good luck!

ALL MINECRAFT TUTORIAL
Colossal Titan Tutorial
Eren's Founding Titan
Rod Reiss Titan
AOT Wall (Maria, Rose, Sina)