Phoronix found some more evidence of upcoming multi-GPU features for Intel's upcoming Xe GPUs. However, unlike Nvidia's and AMD's implementations, Intel may be looking to support a hybrid version that allows Xe discrete cards to be paired with the iGPUs coming with the gen 12 CPUs scheduled to release next year.
https://www.notebookcheck.net/Upcoming-Intel-Xe-discrete-GPUs-may-support-multi-GPU-setups.440252.0.html