If you are using Cloudflare as first line of defense, and want to restrict by IP in the Apache webserver behind. Add this to your .htaccess:

SetEnvIF X-Forwarded-For "1.1.1.1" AllowIP
 
<RequireAny>
Require env AllowIP
</RequireAny>

Where 1.1.1.1 is the IP address that you want to allow access to your site, just replace it by your IP address.