Hello @DevBuster007 , I believe you want each execution to be a blocking call and limit the scale to one instance only.
To achieve that you could modify the App Setting WEBSITE_MAX_DYNAMIC_APPLICATION_SCALE_OUT.
However, if your code is asynchronous, the same app instance can process multiple requests in parallel.
You may also check the Singleton attribute concept here.
https://github.com/Azure/azure-functions-host/issues/912
Please let me know whether this helps. If yes, please "Accept the answer" and "up-vote" so that it helps others in the community.