There are different methods to enable Force HTTPS Redirect.
Method1: in this method, you can Force HTTPS Redirect from cPanel. to enable this, login to your cPanel.
Navigate to "Domains" option inside cPanel, and you can see a button to turn on and off the "Force HTTPS Redirect". Simply turn on the option to redirect all traffic to HTTPS.
Method2: you can Force HTTPS Redirect using .htaccess file. for that from ftp or cPanel file manager add following lines on .htaccess file:
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]