Use WP-CLI to clear the OPcache for a site via HTTP.

# Clear the OPcache for the website.
$ wp opcache clear

# Invalidate a cached script.
$ wp opcache invalidate 'foo/bar.php'

Installing this package requires WP-CLI to be installed on your server. Update to the latest stable release with wp cli update.

Once you've done so, you can install this plugin with composer require wearerequired/wp-cli-clear-opcache.