If you are using cloudflare there is even an easier solution, enable IP geolocation for the domain:
https://support.cloudflare.com/hc/en...IP-Geolocation
You can now do this on your landing page:
Code:
if($_SERVER["HTTP_CF_IPCOUNTRY"] === 'US') $offerUrl = 'https://us-offer-url';
elseif($_SERVER["HTTP_CF_IPCOUNTRY"] === 'FR') $offerUrl = 'https//french-offer-url';
etc etc
header("HTTP/1.1 301 Moved Permanently");
header("Location: ".$offerUrl);
Other options are free APIs like
https://freegeoip.app/ or the maxmind geoip database
https://www.maxmind.com/en/home