iOS13 app should let users permit the use of bluetooth when users launch app first time. However users sometimes do not know this new feature and mistap "don't allow" not use.
I would like to users to use bluetooth even after they pressed "Don't Allow". Is that possible to make it with codes inside app?
No and there shouldn't be. If someone selected "Don't Allow" even unintentionally, you should respect their choice. If have an interesting feature you think they would appreciate, you should consider telling them after the prompt if they choose not to allow it, and you should respect their choice then too.