In September last year, Instagram added a new auto-captions option for IGTV uploads, improving accessibility, which it then expanded to Stories in May this year, enabling users to easily add on-screen text to their video frames.
Now Instagram is looking to make its auto caption tools available for regular feed posts as well, as per this exchange:
That will add new capacity to your feed posts, providing yet another option to improve accessibility, and maximize viewership in both sound on and sound off environments.