It's not automatic, any sufficiently complex interface will need to offer some kind of support. E.g. if your widget library offer dialogs, using e.g. ncurses, then TAB shouldn't allow you to flow out of such dialog. If you render graphic elements with special characters (dots, dashes or unusual glyphs), you would need to offer some hints to the screen reader to skip or identify differently that stuff. Just "read them out loud because is text" wouldn't work. It's been a long time since my last complex TUI so I don't know what's there today for accessibility