The food situation
Nothing, host treats, or everyone brings a dish.
This setting decides whether the event gets a menu. It covers who cooks, not who pays. Splitting costs is a separate setting, so a host can cook everything and still share the shopping bill.
No food or drinks
No menu appears anywhere on the event.
Host's treat
You provide the food. A menu still shows so guests know what is being served, but nobody is asked to bring a dish.
Potluck
Guests bring dishes. A shared menu appears with a portion hint based on how many people have said yes.
Choose potluck whenever you need to coordinate what arrives, even if you are cooking most of the meal yourself. Host's treat is for events where it does not matter what guests bring, or where they should bring nothing.
Note — You can change this after publishing. Switching a potluck to host's treat hides the menu but does not delete it, so switching back brings the claimed dishes with it.