The host controls who can attend a show. For private shows a guest must have an invitation to attend. The host can adjust settings to allow people to receive invitations in several ways:
Only the host can invite people
Hosts can allow artists to invite people.
Hosts can add co hosts who can invite people
Hosts can change setting to allow guests to invite other people
Hosts can allow public to request an Invite
Hosts can send an open link allowing anyone with the link to accept an invite.
Hosts can set the event to public allowing anyone to accept an invitation
The controls for the various show settings are described here.
See how you can invite people to your show