I've also never seen Windows "ask" which cores to use, however it is possible to "tell" Windows which cores to use - you can do this in the Task Manager under the Details tab, by right clicking on a process and choosing Set Affinity

https://www.thewindowsclub.com/processor-affinity-windows

Keep in mind that this would be considered a rather advanced thing to do, with potential performance consequences, but it can be handy for limiting a program that's "hogging" the CPU, or occasionally for very old programs that don't understand multiple processors.


I work here