Although the brand-new OnePlus 9 Pro flagship is available for purchase from multiple retailers, only the ~US$1,000 model with 12/256 GB of memory/storage can be ordered right now. The version with 8/128 GB is nowhere to be found and there is no official information regarding its date of arrival.
https://www.notebookcheck.net/OneMore-Delay-8-128-GB-OnePlus-9-Pro-not-available-yet.530896.0.html