Kodo

Slug-Free Permalinks lets you switch selected post types and taxonomies to simple ID based permalink formats.
You can choose between:
<ul>
<li><code>/post/123/</code></li>
<li><code>/post-123/</code></li>
</ul>
The plugin only affects the post types and taxonomies you enable in the settings screen.
Features:
<ul>
<li>Select individual public post types</li>
<li>Select individual public taxonomies</li>
<li>Choose slash or hyphen based ID permalink format</li>
<li>Optionally redirect legacy slug URLs to the current ID based permalink when WordPress can resolve the request</li>
<li>Preserve prefixed permalink bases such as <code>/en/</code> when another plugin adds them</li>
<li>Flush rewrite rules automatically when settings change</li>
</ul>
This plugin is focused on permalink structure only. It does not add content features or front-end UI.
Plugin page (English): https://happas.jp/en/slug-free-permalinks/ 
Plugin page (Japanese): https://happas.jp/slug-free-permalinks/
Development repository: https://github.com/1008k/slug-free-permalinks
This plugin is best suited to new sites, sites still defining their permalink policy, or structured-content use cases where slug management is unnecessary.
If your site already has a large number of published posts and established slug based URLs, review the impact carefully before enabling it. Check existing inbound links, search traffic, social shares, and editorial workflow assumptions.
Known limitations:
<ul>
<li>If a post type slug and taxonomy slug are identical, their ID based rewrite patterns can conflict.</li>
</ul>

Slug-Free Permalinks – Simple ID-Based URLs

Use ID based permalinks for selected post types and taxonomies without managing slugs.

Boyan Raichev

This plugin converts Bulgarian cyrillic characters in slugs and filenames to Latin characters, according to the official rules for transliteration. Cyrillic letters in URLs, while supported, are ugly and when copy/pasted around the internet are often encoded (converted to those ugly URLs looking like %DU^ED%…)
The plugin automatically converts slugs when a post is created or updated. It also automatically will convert cyrillic characters in filenames, upon media upload. The filename conversion can be disabled through wp-config.php
It will also work for Russian permalinks, as it matches all the letters in the Russian alphabet, although the user should have in mind that there are minor differences in the common transliterations rules in the two languages.
<h4>Features</h4>
<ul>
<li>Automatically converts existing post, page and taxonomy slugs when you save them</li>
</ul>

Bulglish Permalinks

This plugin does exactly what it says! 
Perfect! 

Does what it says!

Simple and light, yet powerful and very useful. Includes necessary features only. Works perfectly well, as expected. No issues while using it for years now.

Amazing plugin for the Bulgarian WordPress community

This plugin converts Bulgarian cyrillic characters in slugs and filenames to Latin characters, according to the official rules for transliteration.

Slug-Free Permalinks – Simple ID-Based URLs vs Bulglish Permalinks