In Azure portal, if I navigate to an existing "Basic" tiered Service Bus namespace and add a new queue to it with the default options and by only providing name (default max size is 1GB) it creates a queue with 16GB max size. If I select 2 GB, I get 32GB max size queue. But when I use the REST API - what I am getting is correct. But on the other hand, if I go to the queue's properties and change the max size to 1GB - it shrinks to 1GB from 16 GB. The same behavior persists for the "Standard" scale as well.
Current Max size enums are 1GB, 2GB, 3GB, 4GB and 5GB