Some questions about apps playing audio

Hey guys!
Maybe in the future I'll buy an iPhone again, and I'd like to know a few things.
1: I use audio description apps a lot, like moviereading for example.
So that the audio description doesn't lag too far behind the movie, I discovered a way, which involves playing an audio repeatedly. this, in this case for bluetooth headphones.
Would it be possible to do this on the iPhone? On Android, there are apps that perform this function.
2: Can I, for example, play a movie on a streaming service and send its audio to Alexa? So, I would play the film's audio and audio description on the iPhone, for example.
If I have more questions, I will update the topic.
Thank you very much, in advance.