Created attachment 136670 [details]
Character properties for Coelacanth font
There are fonts like Latin Modern(1) or the still in development Coelacanth(2) that offers "optical sizes"(3): variants of the font designed to be used for different point sizes (broader, less detailed for small point sizes, taller and with higher contrast for big headings).
This feature is governed by the "size" OpenType table. Systems like XeTeX automatically pick the right font file to be used on the appropriate size, but it seems that LibreOffice gets confused by that table: not only it do not switch between variants, it's not even possible to select which variant is being used as you can see on the attached screenshot. In fact Coelacanth consist of 37 font files tied together by the "size" OT feature, but LibO only offers a small and rather arbitrary selection.
Sounds relevant -> NEW