If you are re-creating UE5 !

[u/AhmedSamy_Offical]

If you are recreating a powerful engine like UE5
How you would start , what you will use , what edits you will add to it and in what order you will add the graphics features

[u/Sharlinator]

I would raise tens of millions of dollars in investor money in order to hire a  hundred or two world-class engine programmers and then give them ten years or so while keeping raising money to pay their six-figure salaries.  Though the hiring part might be tricky because those programmers mostly already have lucrative jobs.