I use Notion as a workbook for learning languages. Some languages (like Lithuanian) are very hard to learn without setting accent marks on new-learned words, because the accentuation may change the meaning of the word.
Even if I could work around the problem by making the accented syllable in bold text, but that wouldn't work for some languages, where there are different ways the same syllable can be accentuated (tone accentuation).
There is a set of Unicode letters for Lithuanian for that purpose -- https://www.unicode.org/L2/L2012/12026r-n4191-lithuanian.pdf. A workaround could be using the Unicode cheatsheet to copy and paste them.