RewriteCond %{HTTP_HOST} ^www.(.*)$ [NC]
RewriteRule ^(.*)$ https://%1/$1 [R=301,L]

RewriteCond %{HTTPS} !on
RewriteRule (.*) https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

DocumentRoot /var/www/public_html

http://example.com        -> https://example.com
http://www.example.com    -> https://example.com

https://www.example.com   -> https://example.com