Quote Originally Posted by Loggos View Post
(Perhaps that's total nonsense though, I'm not a programmer. I just thought of Genshin/Infinity Nikki/Wuthering Waves/etc. who develop the same game for several platforms simultaneously. So I wonder do they really create every version from scratch or can you reduce the workload by using some code/programming across platforms?)
it depend. generally, since thoses games first target is the mobile market, they use either Vulkan or OpenGL as 2D/3D Render API.
OpenGL is the most cross-platform API, while Vulkan was dev for Android but it's based on an AMD technology (And AMD Chipset are used on X-box and PS4/5).

Or they use already well know and cross-platform Graphical Engine (like Unreal Engine, Unity etc...) and Game Engine to facilitate the port to another platform.