This doesn't work for me.
man 5 connman-service.config states that
Description are the only keys allowed in the
global section. If I set
IPv6.privacy in a service file instead, everything works as expected.
Perhaps someone can confirm that setting the IPv6 privacy extensions for connman does indeed not work as described in the wiki, because I'm still not entirely sure if the wiki is outdated in this regard, or I'm doing something wrong.