You will need to install a user script manager extension to install this script.
Reveals cropped portions of content while post is under mouse pointer.
⚠️ Revealed images are same Twitter currently uses for previews: they contain whole area but are still scaled down, so to enjoy better resolution you still have to click for post, and for original resolution open the original image from there.
Highly recommended to use with Unround Everything Everywhere to see whole avatar images and generally get rid of all those pill-shaped elements.
If you'd like to read image alternative texts, try Image Alt to Title.
If you'd like to see which images have and which don't have filled text alternative (accessible text), try Missing alt revealer for Twitter.