Fumiki Takahashi

TAROSKY INC.

Hametuha INC.

This plugin adds a block to your block editor. 
This block changes its display depending on a current user’s capability.
<ul>
<li>You can set capability for block.</li>
<li>If a current user has a capability for the block, its content will be replaced.</li>
<li>Or else, block is displayed as log in link.</li>
<li>This block is an inner block, so you can nest any blocks inside it. Convert it to a reusable block for your productivity.</li>
</ul>
See screenshot for how block will be displayed.
This plugin use REST API to convert block content, so you can use it with cached WordPress. 
Even if you use CDN like <a href="https://aws.amazon.com/cloudfront/" rel="nofollow ugc">CloudFront</a> or <a href="https://www.cloudflare.com/" rel="nofollow ugc">Cloudflare</a>, this plugin displays proper contents for each users.
For performance enhancement, <a href="https://wordpress.org/plugins/cookie-tasting/" rel="ugc">Cookie Tasting</a> is recommended. 
It decrease server access including REST API by checking COOKIE value before accessing to server side script.

For Your Eyes Only

Add a restricted block for specified users.

WP Chill

Awaken Solutions Inc.

This plugin allows you to easily mark certain pages with “Permissions” and only users with those permissions will be allowed to see the contents of the page.
<ul>
<li>
Page Permissions: This plugin adds a new Permissions taxonomy to your pages. Administrators can create/assign new permissions from the Edit Page screen (you can also use the Quick Edit link). You can add/edit/delete permissions from the Permissions sub-menu under the Pages menu. Pages with no assigned permissions can be seen by everyone.
</li>
<li>
User Permissions: Administrators can add/remove permissions from a user using the checkboxes on the Edit User screen. The All Users page has a column that shows the permissions assigned to each user.
</li>
<li>
Restriction Message: If a page has permissions assigned, the content will only be visible to users that have one of those same permissions assigned. Otherwise, the content will be replaced by a generic message or a custom message which can be defined in the plugin settings using the standard WordPress editor (including the ability to add media and formatting).
</li>
<li>
Redirect to login: Instead of a restriction message, you can choose to have users get redirected to the login page.
</li>
</ul>

Simple Restrict

Restrict pages based on permissions assigned to pages and granted in user profiles.

For Your Eyes Only vs Simple Restrict