RewriteEngine On

# www -> non-www + https
RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^ https://%1%{REQUEST_URI} [R=301,L]

# http -> https
RewriteCond %{HTTP:X-Forwarded-Proto} !https [NC]
RewriteCond %{HTTP:Forwarded} !proto=https [NC]
RewriteCond %{HTTPS} !=on
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L]