Draw calls optimization for mobile platform

I am newbie with game development, I am programmer with c++, but decided to develop my own mobile game. The problem is with optimization, especially I have a very big trouble with “draw calls”. There are a lot of calls, more than 1500.
My game has a lot of static meshes (each has three textures: base color, normal map and metalness&roughness, generated with “Substance Painter 2”). One static mesh is some element (Bridge pillar, Road surface, etc ). Using meshes I have created Blueprints elements (Bridge section, Lifts, Buildings, etc). Using that Blueprints elements I am creating my own game levels. Also I’m planning generate any random game levels at runtime, where I will use these Blueprints elements. On the web I have found information about texture atlases, that can significantly optimize number of draw calls. But I could not find any information about it. Please advice how can I reduce count of “draw calls” I spent a lot of time to find some solution but with no luck.

As I see, no one knows the answers to the question…:mad: