I understood that Azure supports availability zones for the following regions
Following regions are supported for availability zones in Azure cloud as of now,
Central US
East US
East US 2
West US 2
France Central
North Europe
UK South
West Europe
Japan East
Southeast Asia
However I don't find any further details like how many zones are there per region? Would it be always 3 per region? Where do I check?
Each Azure Region with Availability Zones enabled will have at minimum 3 separate Zones. This is to ensure maximum resilience and high availability can be enabled within the Azure Region. therefore there's no point of showing more than 3 zones as this will not increase the SLA.
Check this for more info about availability zones