No, it’s practically impossible for one person to know everything in Unreal Engine.

1. Unreal Engine is enormous

Unreal Engine (especially UE5) is one of the largest and most complex codebases ever made for real-time graphics.
It’s tens of millions of lines of C++, covering:

• Rendering (deferred, Nanite, Lumen, path tracing, shaders)

• Physics (Chaos, destruction, cloth, vehicles)

• Animation (Control Rig, IK, blendspaces, motion warping)

• Gameplay Framework (Actors, Components, Subsystems)

• Networking (replication, prediction, RPC)

• Editor tools (Slate, Editor Framework, Asset System)

• Build tools (UBT, UHT)

• Plugins, audio, AI, scripting, etc.

Each of these areas is a career specialization on its own.

2. Epic Games itself uses teams of experts

Epic has hundreds of engineers, each focusing on very narrow areas.
For example:

• One team only works on Niagara (particle system).

• Another focuses purely on Lumen lighting.

• Another on Chaos Physics.

• Another on Unreal Editor UI.

• And many on gameplay framework.

Even within Epic, no single person knows everything — not even Tim Sweeney (the founder) keeps track of all systems in detail anymore.

3. The 8-hour compile time tells you something

That’s not just slow hardware — it’s because the codebase is huge and interdependent.
Even understanding how everything connects would take years, not months.
And by the time you do, the engine changes — Epic updates UE every few weeks with major architectural refactors.

But here's the hopeful truth

You can become an expert in a slice of Unreal Engine, and that’s all you need to:

• Make a AAA-quality game

• Modify the engine itself

• Or even build your own simplified version (many people do this!)

If you pick a focus (for example, “Rendering and Materials” or “Gameplay Framework”), you can master it completely   and you’ll understand more of the engine than 99% of developers.

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Even people who work on Unreal full time (Epic engineers) often say:

“I still discover new parts of the engine I didn’t know existed.”