File tree:
app/design/frontend/MyVendor
└── child_theme
├── Magento_Cms
│ └── layout
│ └── cms_page_view_selectable_product-finder_ProductFinderLayout.xml
├── composer.json
├── registration.php
└── theme.xml
registration.php
<?php
use Magento\Framework\Component\ComponentRegistrar;
ComponentRegistrar::register(
ComponentRegistrar::THEME,
'frontend/MyVendor/child_theme',
__DIR__
);
theme.xml
<parent />
= parent theme yours is inheriting from
<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
<title>MyVendor - Child Theme</title>
<parent>Magento/blank</parent>
</theme>
cms_page_view_selectable_product-finder_ProductFinderLayout.xml
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceContainer name="content">
<block name="test" class="Magento\Framework\View\Element\Text">
<arguments>
<argument translate="true" name="text" xsi:type="string">Some Custom Text</argument>
</arguments>
</block>
</referenceContainer>
</body>
</page>
Configuration:
- In the admin, make sure the theme you mentioned is the one set for this website
- Under Content > Design > Configuration
- Clear cache after configuration changes
- Edit "Product Finder" CMS Page
Design Configuration

CMS Page Custom Layout Options

https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/layouts/xml-manage.html#create-cms-pageproductcategory-specific-selectable-layouts
Selectable layout updates can only be loaded from the global store theme and work only in the single website with single theme configurations. If a specific entity like cms-page/product/category has an individual theme applied in the design configuration tab, the selected theme will have priority over the selected layout update.