WP Htaccess Editor

Perform quick changes to .htaccess file, directly from the WordPress dashboard, with the safety net of automatic backups. The plugin also features a simple syntax checker, potentially catching the worst typos in your .htaccess file, and a solid explanation of how to resolve from a messed up configuration. Which you should read 😉

Extract from WordPress.org

WP Htaccess Editor provides a simple, safe & fast way to edit, fix & test the site’s htaccess file from WP admin. Before saving, htaccess file can be tested for syntax errors. It also automatically creates a htaccess backup every time you make a change to the htaccess file. Htaccess backups can be restored directly from the plugin, or via FTP if the errors in htaccess file prevents WP from running normally.

https://wordpress.org/plugins/wp-htaccess-editor/