Enhanced Typesetting allows improved rendering of e-book content using hyphenation, kerning and ligatures.
"Enhanced Typesetting, multi-thumbnail Page Flip, non-justified alignment, continuous scrolling, page curl, Guided View for comics, and sticky notes (on Kindle Scribe)."
https://www.mobileread.com/forums/sh....php?p=3288333
That's what it's called, enhanced typesetting