One of the things you need to do in order to redirect from HTTP to HTTPS is to add this into your .htacess file at the root level of your WordPress install.
<IfModule mod_rewrite.c> RewriteEngine On RewriteCond %{HTTPS} off RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301] </IfModule>
A couple more things you need to do can be found at this site:
https://websitesetup.org/http-to-https-wordpress/