Selling in multiple currencies is being released gradually. A notification will appear in your Shopify admin when your store can start to use this new feature.
List of limitations for selling in multiple currencies.
Exclusions and limitations
Selling in multiple currencies is only supported by Shopify Payments.
Selling in multiple currencies is supported in your online store only. Shopify POS supports only your store currency. You cannot sell in multiple currencies in any channels (including the Wholesale channel).
Debut is the only Shopify theme that has a built-in currency selector.
Draft orders are always in the currency of your store.
You can view your reports only in your store currency.
You can't set specific prices based on country while selling in multiple currencies.
Sofort payments and Klarna Pay Later are available only for merchants in Germany selling in Euros.
iDeal payments is available only for merchants in the Netherlands selling in Euros.