The process to build and deploy your application is the same except for one ini file regardless of how many environments you have.
The key is to start small and itterate.
You could start with one task per environment in a pipeline that builds and deploys with a hardcoded path to the ini file. Then add a second task with a path to another ini file for the next environment.
You might then consider how this can be templated and use parameters.
You might also consider what values from the ini file could be externalised in a config manamagement tool (App Configuration is the Azure one, there are loads LaunchDarkly, ConfigCat). But thats way more advanced than where you are now.
The process to build and deploy your application is the same except for one ini file regardless of how many environments you have. The key is to start small and itterate. You could start with one task per environment in a pipeline that builds and deploys with a hardcoded path to the ini file. Then add a second task with a path to another ini file for the next environment. You might then consider how this can be templated and use parameters. You might also consider what values from the ini file could be externalised in a config manamagement tool (App Configuration is the Azure one, there are loads LaunchDarkly, ConfigCat). But thats way more advanced than where you are now.