You have to follow below steps in Plesk:
- Login to Plesk.
- Click on”Websites & Domains” which is available on left side panel.
- Here click on “Hosting Settings”, where under “Security” section you will find “SSL/TLS support and Permanent SEO-safe 301 redirect from HTTP to HTTPS checkboxes”.
- Select the required certificate which is suitable for your website.
- At last, click on “Ok”.