@SashimiEthan forwarded a question about getting visual alignment at the start/end of the line see testcase and diagram:
:

Turns out there's an OpenType feature for this (at least, in horizontal text), which is expected to be on by default. Should we note this in the spec or something?

https://docs.microsoft.com/en-us/typography/opentype/spec/features_ko#tag-opbd

This feature should be active by default. It effectively changes the line length, so justification algorithms should account for this adjustment.

If we want control over it, I'd suggest adding to the font-kerning property: it's effectively kerning with respect to the start/end edge.