We normally say 'es teh'. When it comes to iced drinks, we usually use 'es' in front of the name of the drink, like es jeruk, es kopi, es cendol, etc. But, in certain regions in Indonesia (I think in some parts of Sumatra or Kalimantan), people say 'teh es' rather than 'es teh'.

Why not teh es? Or is es teh a particular product, like ice tea? I only know it as ice tea, not as iced tea, when referring to the pre-made sweetened cold tea with citrus flavour.

Yes, it's always called like that in Indonesian, "es teh".
It's never called "teh es".

I just thought the same. Maybe due to english or dutch influence