Yes! Adding C++ code to your game is not as straightforward as adding GDScript or C# code, but it is about the same complexity as C++ in any other game engines. There are two main ways of using C++ in Godot:
GDExtensions are a way to add C++ that don't require you to recompile the entire engine just to add some new code. Getting started can be a lil tricky, but there are good resources out there to show you how to do it.
You can also download the engine source from Github. Even if you don't know Git, you can still download it. With the full source, you can add your own new code or change existing code in the engine, but you will need to fully compile it each time you make a change.
Are you familiar with other programming languages? It might be hard to get started with C++ in Godot without knowing the basics of programming first. There are resources out there for learning C++ as your first language, but none that I know use Godot, and C++ can be a tricky language.
