Currently controls to enable or disable community account creation can only be done globally across all ArcGIS Hub initiatives within an organisation (https://doc.arcgis.com/en/hub/community/configure-community-sign-in-prompt.htm#ESRI_SECTION1_C30D733...). It would be preferable to be able to set this at the level of the initiative as well, as we have some initiatives where we only want to be inviting community users to create accounts, and others where we would want users to be able to create their own community accounts.