We use Classic Editor for pages and posts in our themes because the Gutenberg is not necessary for a tube site.
To create a default WordPress Page go to Dashboard -> Pages and create a new Page by clicking on the Add New Page button on the top.

Add your content, shortcode or whatever you wish and use the editor toolbar to highlight texts or insert images, alternatively you can use Template dropdown in Page Attributes section which appears on the right sidebar of your page editor.
There are 4 Templates in POPCORN Theme, Videos I Like, Performers, Categories and Homepage(required for seo)

As you can see in the screenshot Videos I Like is selected as Template, you have to create a new page without content for each template you see in the dropdown list.