To have conditional logic applied to your thank you page, you can either:
Option A - Conditionally change the URL of the thank you page based on values of fields:
First open the "Thanks Page" module from the right side menu:
Make sure that "Redirect to a different URL" is selected, and that you have specified a thank you page URL. Then click the "Add Conditional URL" button to specify a conditional alternative URL:
Option B - Send form field values to a thank you page, and apply conditional logic to that page:
In this scenario we pass form submission values to a GlobalPatron form that is acting as a "Thank You Page". Because our thank you page is actually a fully functioning form it has functionality for customization available to it like showing/hiding particular fields based on Conditional Logic, or pre-populating of fields.
More details on how to do this are below:
How can I create a custom thank you page?