Tools > Options > Writing Aids and Tools > Language > More dictionaries lead to the extensions website, filtered for dictionaries. This should be replaced by the internal dialog.
Heiko Tietze committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/core/commit/acb1c390539730957fb509f18f469fc7f6133082 Resolves tdf#137187 - More dictionaries via extensions dialog It will be available in 7.1.0. The patch should be included in the daily builds available at https://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More information about daily builds can be found at: https://wiki.documentfoundation.org/Testing_Daily_Builds Affected users are encouraged to test the fix and report feedback.