Post Templates allow you to use different layouts for your blog posts or website pages. WordPress themes usually come with various built-in templates, but you can create your own.
To create your own custom template, go to the Site Editor (from the WordPress dashboard, Appearance > Editor).

On the menu on the left, select the Templates button.

When the Templates menu opens, click the plus button and select the Custom template option.

Assign a name to your new custom template and hit the “Create” button.

Once you’re done, you will be brought to the Template Editor and you should be able to see it in the Templates menu.
