There are 2 steps required to make your Wordpress uses HTTPS (SSL) connections by default:

first be sure that your SSL certificate is already installed, in most cases its already installed automatically, test your website first using http

1. Configure Wordpress to use HTTPS urls from your wordpress admin area > settings > General

and use https URLs as below

by doing this steps, all your website links generated by Wordpress will use https, but when typing the domain in the browser, the normal non-https website will be loaded by default, and step 2 will fix that.

2. add the following 2 lines code into your .htaccess file

RewriteCond %{SERVER_PORT} !^443$
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

You can edit the .htaccess using the command line or edit .htaccess file using the file manager of cPanel

Your Wordpress website now is using HTTPS by default and all internal links will use HTTPS connections.