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 and a read-only version of the submitted record. 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
These options above are all found under After Submission in the Submission Actions section of the form settings.
In addition, you can also send a confirmation email to the admin, or the end user, as explained here.
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!
You can also define a Redirect Delay (in seconds) so that the success message is visible for longer. This can also be useful when an automation or similar needs to run before the redirect takes place. Adding a delay can ensure that the workflow can complete first.
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.