Instagram has the same automatic alt-text generation feature as Facebook. To add custom alt-text/image description, open “Advanced Settings” at the bottom of the screen when you are creating your post. Then select “Write Alt Text” at the bottom of the Advanced Settings menu.
Then, you will be able to craft your description. Remember to keep context in mind, and be sure to describe the photo in a way that you are providing and equivalent experience for users that may not be experiencing your content visually.
Adding Video Captions
The platform currently does not have any captioning features within the app.