By default, your Space will always be set to Only people you invite to speak. You can also modify the Speaker permissions once your Space has been created. Tap the {{ twtr-rte-icon:more }} icon, then tap Adjust settings to see the options for speaker permissions, which include Everyone, People you follow, and the default Only people you invite to speak. These permissions are only saved for this particular Space, so any Space you create in the future will use the default setting.
Once your Space has started, you can send requests to listeners to become speakers or co-hosts by tapping on the {{ twtr-rte-icon:people }} icon and adding speakers or tapping on a person’s profile picture within a Space and adding them as a co-host or speaker. Listeners can request to speak from the host.
Hosts can also invite other people outside of the Space to speak via DM.