Inorder to practice english listening skills, delay the subtitle is a good idea, I suggest you can supply the function that subtitle can delay 2~3 seconds
I’m not the developer, but I would imagine subtitles are shown at the same pace Netflix sends them, and to introduce a delay would likely be impractical, not to mention confusing when dialog is very fast.
To hone listening skills, maybe consider turning all subtitles off for a portion of the show, say 5 min at a time, then re-watching with them on (or vice-versa).
