Is there a way to hide fields based on the change in value on the same page?

Summary:

We have custom fields which needs to be displayed based on the category selected in the create service request page?

The flow is not working as we believe the flow is executed before the page is loaded so even if we create multiple templates and add them in to the flow based on category its not working.

How can we hide field on the page based on change in the value of a different field. For example: I have field PTO Hours that should be display if the category is selected as PTO in the Create Service Request page.