These options are only available for standalone forms, not child forms (i.e. forms used in a portal or shared view or for linked record fields in a main form).
By default, the form just shows a standard success message. However, you have many options to customize what happens after submission, for example:
Show a custom success message
Redirect to a URL
Allow users to submit another form
Redirect to a new form
Allow users to copy the submitted record to a new form
Trigger a webhook
Show a custom success message
This custom message could either be static or coming from an Airtable field, for example when you want to use data from the submitted record. Set a Success Message Delay when you are using an Airtable field as a source of the success message to ensure that creation or update is already finished prior to displaying the message.
Redirect to URL
This redirect URL could either be static or a value of an Airtable field. You can use this to redirect the user to another form, for example, or to a specific page. If the field used as the redirect target is a formula, you can even make this dependent on the data in the record, so that the user is redirected to one page if a checkbox is checked, for example, or to another one if it isn't!
Close the form
A success message will be shown to confirm the successful submission and then the form will automatically close after some time. Set a delay to provide enough time for your users to read the success message. This article explains how to set this up.