I'm unable to find the details in Bitnami Wordpress documentation, but if I use it in Azure, do I also need to setup a managed disk? If yes, how can I configured Bitnami to use the managed disk instead of the OS disk?
Bitnami Engineer here. The WordPress solutions we provide in Azure don't use managed disk by default. All the components and files are included in the same instance so if you want to use a different disk, you would need to create that new disk, move the data to it and attach it to the instance.
Please remember that you will need to continue using /opt/bitnami as installation directory so if you mount a new disk, you will need to create a symlink to link /opt/bitnami with the files in the new disk.
I hope this information helps.