How does Unreal Engine work under the hood - Architecture

Is there anywhere we can read about how Unreal engine works under the hood fully. So that I may complete this assignment below


You are required to investigate four different game development/engine frameworks. Three of the frameworks/engines are Unreal, Unity and Cocos-2dx, the last framework/engine is your choice

Requirements for the report are as follows

1- Word count 2000 to 4000 words
2- When analysing each framework/engine you must consider the following Architecture features
a. Processors
b. Graphics
c. Audio
d. controllers
e. Storage
f. Platform interfaces

3- As part of the report consider the Cross-Platform implications for each one. These can include:
a. Issues in achieving cross platform game operation
b. Developing for different platforms
c. Language and scripting
4- Identify four mobile game genres and which framework/engine you would each and why.
5- Finally conclude with lessons that you have learned from using engines/frameworks during your time on this degree programme

Thanks

Your question is really interesting but I think you complicated your assigment too much or school/cource you are are attending is really, really advanced. I think the asigment should be just a case study of features and maybe you implementing a basic scene in all 4 and comparing and documentation pages and even some overview tutorial would be enough for this.
On the other hand I would too realy like to see such a document about engines arcitecture and belive there got to be something like that considering the number of external devs creating pull requests for the engine. So if you did find such a document sharing the link as answer here would I belive be of much value for a lot of people.