Do the bedrock edition Minecraft dedicated servers support multithreading? According to the wiki, the client does, but I could not find anything about the server.
You can see a thread count of 25 threads. How much the bedrock server is optimized for multithreaded performance is another story. It's proprietary software so there isn't a way to verify that. Several factors besides threading affect performance. IO can be a big performance factor with Minecraft servers for instance.