The linux kernel has had SMP support since the 90s. Any distribution you pick will have this support. You might try playing with the various scheduler options by compiling your own kernel. Having used both gentoo and archlinux in the past, I'd recommend starting with something with prebuilt packages and look at the documentation on recompiling the kernel for your needs. Look at the various optional schedulers. This archwiki entry will be pretty close to what you need on Cachy https://wiki.archlinux.org/title/Kernel/Traditional_compilation . These are the scheduler options https://docs.kernel.org/scheduler/index.html . I think that most kernels use the CFS scheduler these days, but I could be misremembering.
Linux
Optimize performance for what?
Seriously. This is the question you need to answer.
Dual xeon sounds like you have some kind of server motherboard with two distinct multicore xeon processors. Which would make your question partially make sense because your memory would be split into two NUMA nodes and cause all kinds of weird issues for generic workloads.
Usually these servers run specialized software that is implemented to handle this case, but generic software (browsers, games) does not. Just recompiling and choosing a distro will not solve your issues. You are probably better off disabling one cpu and numa node or configuring them to not run, to avoid the data split.
If you want to optimize for server workloads for server software (webserver, db software) then a good and stable server distro is all you need (debian, almalinux).