PIE, Block Editor Options
The WordPress 5 block editor is disabled by default. Site administrators can choose to enable the block editor or can allow users to select an editor each time they edit content.
Default Editing Experience
From your WordPress dashboard visit Settings -> Writing to review the "Default editor for all users" and the "Allow users to switch editors" settings. Initially the "Default editor for all users" will be set to Classic Editor and "Allow users to switch editors" will be set to No. With these settings in place, the editing experience will be exactly the same as it was before the Block Editor was introduced.
From the Dashboard, the Pages menu lists all the pages on your website. Hovering over the title of a page displays the action menu. The action options are Edit, Quick Edit, Trash, and View.
Clicking Edit will open the classic editing experience.
Changing Editor Settings
From the Dashboard, visit Settings -> Writing to change the default editor.
With Block Editor selected as the default, the pages list will look exactly the same. When you hover over a page title, the actions displayed will read Edit, Quick Edit, Trash, and View
When a users clicks Edit, however, the Block Editor will open rather than the Classic Editor. The Block Editor allows users to place and manipulate content, formatting, and layout blocks. Content that was originally created using the classic editor will be placed in a classic editor block.
When working with content inside the classic editor block type, the block header expands to reveal all of the formatting tools available in the native classic editor. For more information about using the Block Editor, see The new Gutenberg editing experience from WordPress.org.
Allowing Users to Choose
From the Dashboard, choose Settings->Writing to select whether or not users should be able to choose an editor each time they edit content. Select Yes next to "Allow users to switch editors" to grant users this ability.
When users are allowed to switch editors, your Pages list will have different action options. When hovering over the title of page, the available actions now read Block Editor, Classic Editor, Quick Edit, Trash, and View. Authors can click either Block Editor or Classic Editor to edit the content with their preferred editor.