Greetings, Edith (@edithmair1)!
Forgive me for intruding, but, to clarify your question, 'Unterschneidung' is called 'kerning' in English (Typografie).
Typolexicon covers kerning, auf deutsch, at the URL, <https://www.typolexikon.de/kerning/>. I know kerning from desktop publishing.
Is your question about kerning text in Fediverse messages? (I am sorry that my German is rudimentary amd very "rusty" from lack of use.)
Happy New Year, Edith! 😊
Cordially,
David