How do you model the characters?

when you want to model a character or a car, wich tool of unreal engine do you use?, if the answer isn’t in unreal, please tell me what do you use?

The engine does not come with modelling tools. You need an external program. Blender / 3ds Max / Maya are the most popular ones. There are more.

Blender is open-source and free - your best starting point. Get ready for a steep learning curve if you’re new to all this.