Hello there, so you want to create a GTA alike game cool, is great that you want to have a Santa too.
But let's get into the ground, doing GTA could cost millions of dollars and thousand of developers, it's a highly detailed open world game, fully extensive, with tons of missions, cars, props, etc. That takes too many resources!
Maybe you want to create something smaller?
What is the reason of creating this game? Perhaps I can guide you, and help you get to a more affordable solution.
What is your budget for this?
I'm happy to assist.