Usually CyberPanel will automatically issue Let's encrypt SSL cert for both www and non-www domain, but if in rare case it failed to issue WWW cert , you can extend the SSL for www domain manually
1. Run command (change example.com to your domain for ALL steps)
certbot certonly --webroot -w /home/example.com/public_html -d example.com -d www.example.com
and enter E during operation
2. Now new cert is issued successfully, we need to replace them with existing ones.
ls -ln /etc/letsencrypt/live/example.com
Now we see where the files are stored , we are gonna replace them.
3. Copy and overwrite the old cert with following commands (please adapt path and files name accordingly to ones you have from step2 )
cp /etc/letsencrypt/archive/example.com/fullchain2.pem /usr/local/lsws/conf/vhosts/SSL-example.com/fullchain.pem cp /etc/letsencrypt/archive/example.com/privkey2.pem /usr/local/lsws/conf/vhosts/SSL-example.com/privkey.pem systemctl restart lsws
4. Open browser and check if everything works out as expected.