Hi anonymous user
Welcome to Microsoft Q&A! Thanks for posting the question.
Unfortunately, currently you cannot set the TTL for the -poison queue using any configuration. I have passed your feedback to the team and you can also pass your feedback/product improvement here.
As the workaround only for .NET Azure function to change the TTL value for now you would have to register your own QueueProcessor and you need to follow this as described here. You would create your own startup class, and register your own IQueueProcessorFactory as we register the default one here. You can also refer to the example in our tests here.