could be I am lost, but currently I don’t see an option to do that. If one want to have global management also for the menu typo, one has probably to work with a sequence of buttons instead (wrapped in div), because buttons could be assigned a global block typo.
correction, changed it to bugs: Option seems to be there, I set the global block typo and assigned it to the menu block on 2 levels (Tab “design” and tab “primary” subsection “main” and “items”). It does apply changes in typo size nor in changes of the typo thickness. What it does, is to adapt typo decoration