Step 1: Open cPanel
Step 2: Find the File Manager application
Step 3: Go to the site folder. If it has only one site, then it is the /public_html folder, but if you have multiple sites, look for exactly which folder is used by the site you want to automatically redirect to https.
Step 4: Create a new .htaccess file or if it already exists then just add these lines to the .htaccess file:
# https
RewriteEngine On
RewriteCond %{HTTPS} !=on
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R =301]
Save this file, and clear the cache of your browser.
Your site will then redirect automatically to https.