How are you checking if the parameters are being applied to the services configuration?
If you want to have several sites in the same WordPress machine, I would recommend to check this stack: https://bitnami.com/stack/wordpress-multisite/cloud/azure.
Here you have documentation on how to configure the sites to be accessed in different ways:
About the performance issues, are you going to have more than 100.000 concurrent users? That is a lot of load.
Note that the VMs are already using an optimized configuration depending on the size of the instance. You can check the different options in files like
/opt/bitnami/mysql/bitnami/my-*.cnf. Depending on the size of the machine, you will have a symbolic link to a different file. You can check this by executing:
$ ls -l /opt/bitnami/php/etc/bitnami/common.conf /opt/bitnami/mysql/bitnami/my.cnf
lrwxrwxrwx 1 root root 39 Jun 15 11:21 /opt/bitnami/mysql/bitnami/my.cnf -> /opt/bitnami/mysql/bitnami/my-small.cnf
lrwxrwxrwx 1 root root 46 Jun 15 11:21 /opt/bitnami/php/etc/bitnami/common.conf -> /opt/bitnami/php/etc/bitnami/common-small.conf
In the example above you can see how
my.cnf is a symbolic link to
my-small.cnf. Are your files pointing to the proper configuration depending on the size of your machine?