Turning off auto lock

I have an iPhone 11 Pro running iOS 13.3. The auto lock option “never” is missing. The most I can select is to auto lock after 5 mins. But the phone doesn’t even wait that long before locking.

The problem is Siri asks me to unlock the phone before I can send or read text messages etc. I’m not always able to lift the phone to my face to unlock it. So how can I turn off auto lock? It’s annoying!