Unreal engine is an incredibly heavy engine and I've only dabbled but here are some of my tips:
1. You can reduce the install size of the engine from a default of over 100GB down to a much smaller install size by adjusting your installation from the Epic Launcher or whatever. You basically can choose to remove a lot of the dependencies for different build platforms you may not be using and also default assets.
2. It might be tempting to try to use C++ but it's not really that simple and there's a lot of caveats built into that work flow, it may be best to just utilize the blueprints visual scripting because it allows you to move them around easily. From my experience organizing C++ in an Unreal project is nearly impossible because they don't let you make folders and stuff. I think the proper way is to build what are called modules but I haven't figured it out myself.
3. Unreal Engine is incredibly opinionated about how things are done. It has an idea of what a Character, Actor, Pawn, etc are and how they function. If you try to go against that you will be fighting an uphill battle. Whereas Unity and Godot give you essentially full control over structure of how you want to build your game, Unreal is extremely opinionated about what each thing is and what it does.