@prasantc Thanks for posting your question in Microsoft Q&A forum. Apologize for any inconvenience caused on this.
Based on the shared information, I have understood that you want to change the default config of nginx which is running on php 8.2 runtime in app service.
To test this behavior, I have created an app service with php 8.2 runtime in one of our subscriptions. Connected to it using SSH console and I can see the default conf file under the path /etc/nginx/sites-available/default
instead of /etc/nginx/conf.d/default.conf
.