How to run code in UEFI at certain addresses in memory? How does addressing work in x64 mode?

Question

C++ / C#

I have a System "Kernel" under UEFI that calls Exitbootservices() and fills the screen with one color. I'm trying to implement multithreading following the example of this article (purely in theory, redoing the code for myself) https://habr.com/en/post/570664/?_ga=2.163432308.9
... from one part or another, on which it ended last time. Under bios this could be done with jmp *** (address in memory) But how to do this under UEFI?