These commands can only be accessed after you enable support for Asian languages in LibreOffice - PreferencesTools - Options - Languages and Locales - General.
このコマンドの見つけ方
Choose LibreOffice - PreferencesTools - Options - Languages and Locales - Searching in Japanese.
区別しない字種・字体・表記
Specifies the options to be treated as equal in a search.