Here are some lesser-known and useful plugins :

1. Advanced Custom Fields: This plugin allows you to add custom fields to your posts, pages, and custom post types. It’s incredibly flexible and can greatly enhance your ability to customize your website’s content.
2. Redirection: Redirection is a powerful plugin for managing 301 redirects and keeping track of 404 errors. It helps you redirect old URLs to new ones, fix broken links, and improve your site’s overall SEO.
3. WP Rocket: WP Rocket is a caching plugin that improves the speed and performance of your WordPress site. It offers features like page caching, lazy loading, database optimization, and more.
4. Sucuri: Sucuri is a security plugin that helps protect your website from malware, hacking attempts, and other security threats. It provides features like security monitoring, malware scanning, and a firewall to keep your site safe.
5. UpdraftPlus: UpdraftPlus is a backup plugin that allows you to schedule automatic backups of your WordPress site. It supports various storage options like Dropbox, Google Drive, and FTP, making it easy to restore your site if something goes wrong.