Can I give every structure entry a custom layout by using the same template?
You can setup a dynamic route for /handle/&lt;slug&gt;/followuppage and route the requests to your follow-up page template. From that template you’d have access to a variable called slug that you would then use to query for your structure entry.

{% set entry = craft.entries.section('mystructure').slug(slug).first() %}

{% if not entry %}
    {% exit 404 %}
{% endif %}