Description
With this plugin, you can easily see which templates have been assigned to each page in the list. It is mandatory if you have a theme with many templates and pages, with this plugin you will easily identify them.
Now you can filter by the name of the template, so easily locate pages that use the template.
We’ve also added the template Slug name as a class in the body of the Gutenberg editor as well as in the front of the template to better encapsulate the styles if you need it.
More information in Spanish about the plugin in the link Improve your template management on WordPress
Links
Screenshots
Is created the column Template, where it shows the templates that are used. 
Filter templates by name. 
Result of filtering by template “Landing”. 
We show the template that is used in the administration bar. 
We add a CSS class to the body whose name is the slug of the template. 
We add a CSS class to the body of the Gutenberg editor whose name is the template slug.
Installation
Extract the zip file and just drop the contents in the wp-content/plugins/ directory of your
WordPress installation and then activate the Plugin from Plugins page.
Reviews
Contributors & Developers
“show template name” is open source software. The following people have contributed to this plugin.
Contributors
Translate “show template name” into your language.
Interested in development?
Browse the code, check out the SVN repository, or subscribe to the development log by RSS.
Changelog
1.0.2
- Compatibility: WordPress 6.3.1 – WordPress 6.5.3
1.0.1
- Added CSS class with the template slug in the body of the WordPress editor and template.
- Change icons and banners for the WordPress repository.
0.4
- Fix some PHP errors.
0.3
- Show in the top admin bar the name of the current template.
- Fix some PHP errors.
0.2
- Filter by template name.
0.1
- Initial release.