They control the pop-up that appears the moment a customer fills the last meal slot for a delivery on the meal-selection page:

• If Ask for Extra Meal or Addons? is Show (and extra meals are allowed for the plan), an almost done pop-up asks whether they want to add extra meals or add-ons before continuing.
• Otherwise, if All Meals Selected is Show, a simple all meals selected confirmation pop-up appears.
• If both are Hide, no pop-up appears.

When the plan auto-selects meals, the pop-up is delayed about 20 seconds so it does not interrupt the auto-fill.