iPhone can provide subtitles, closed captions, and transcriptions so you can follow along more easily with audio and video.
When you play video content in a supported app, you can turn on subtitles and closed captions (if available). iPhone usually shows standard subtitles and captions, but you can also choose special accessible captions—such as subtitles for the deaf and hard of hearing (SDH)—if available.
While playing video content, tap Accessibility features for hearing on iPhone