@Niren Adhikary (NAD) Thank you for reaching out to Microsoft Q&A.
Based on the shared description I have understood that you are using custom identity provider authentication in static web apps. Custom identity providers are configured in the auth section of the configuration file. To avoid putting secrets in source control, the configuration looks into application settings for a matching name in the configuration file.
You can create multiple environments for dev, uat and prod by using any of the deployment types as mentioned here and with different application settings name and their values accordingly.