I checked and it can be added by custom code, this is changed by JS.
It is a complex requirement and it is difficult for me to guide you through it in detail, but you can hire an expert for it, they will help you add this feature quickly. Refer group: https://community.shopify.com/category/shopify-job-board
The first thing you’d check is if the actual underlying variant is different for each regions size by adding to the cart.
And disable javascript and try to add to cart,etc
Check the other regions product page behavior, etc
That can inform if they are using multiple variants, or possibly an app.
Moreso if the example is multichannel and you can find regional based products.
If the actual variants aren’t changing and the option values have a consistent relation then it’s either a data map used in javascript or liquid to set the correct values.
It’s also possible the values exists as translation keys that are used by checking the value of the actual size option.
If you need something like this customized you may contact me directly. Contact info in sig, please provide context: post urls, store urls, theme name, and any issue details,etc.
This is is one of those missing features in Shopify that shocks me.
I have seen in the Community both Shopify staff and partners recommend using Shopify Markets (hammer & nut solution) and thats got limits eg standard monthly plan only allows 3 markets. Also (as here) I see partners descrivbing it as complex and fishing to be hired to do this as customisation work. After a search and some outreach in the Shopify App store, it seems all the top Size Chart / Size Guide app providers say its beyond their scope. So its dead end.
Anyone got any good ideas eg could MetaObjects handle this!?!
