If you want to make WordPress as a backoffice system, this plugin can help you disable WordPress features you do not want.
This plugin can:
<ul>
<li>Disable posts, media, comments, pages, XML-RPC.</li>
<li>Disable all front-end pages. It will be redirect all URL in the front-end to wp-admin page.</li>
<li>Disable posts, media, pages, author page for front-end only.</li>
<li>Disable parts of admin pages such as greeting message, plugin file editor, theme file editor.</li>
<li>Disable user profile fields in add new user, edit user, edit profile pages. The fields can be disabled such as Admin Color Scheme, Website, Biographical Info.</li>
</ul>

Rundizable WP Features

Disable WordPress features such as posts, comments, pages, media, all front-end or partial.

Tassawer Hussain

2ByteCode

All-in-One Utilities is a versatile plugin that allows administrators to streamline their WordPress site by enabling only the necessary features. Reduce site overhead and manage user roles and settings efficiently with these key features.
This plugin consolidates the functionality of several popular plugins into one lightweight package: 
– Default Featured Image 
– Easy Username Updater 
– Multiple Roles 
– Disable Everything
<ol>
<li>
User Multiple Roles: Assign multiple roles to users during creation or editing.
</li>
<li>
Username Updater: Easily update usernames for users via a dedicated action in the Users list table, with optional email notification.
</li>
<li>
Default Featured Image: Choose a fallback featured image in Media Settings that is applied when posts/pages lack one.
</li>
<li>
Disable Unnecessary Features: Toggle off various WordPress features (e.g., author archives, application passwords, adjacent posts, embeds, emojis) to streamline and speed up your site.
</li>
</ol>
<h3>License</h3>
This plugin is licensed under the GPLv2 or later.

All-in-One Utilities

A must use plugin for any WordPress site with necessary features.

Rundizable WP Features vs All-in-One Utilities