Hey Marcel! @marcelkriegs
Thanks for the question and you have reached the German community here in case you want to discuss this in German instead. But English is fine too!
Most cross-border-selling translation apps offer a convenient lang-switcher in the header bar and you can choose to use country flag icons to improve the language switching experience for your customers. Do you also want to allow for currency switching?
The Geolocation App is a GeoIP redirect app from Shopify and it ties in nicely with these apps to automatically detect the location of the visitor to your shop and switch the language as well as the currency (if you are using Shopify Payments multi-currency feature) accordingly (see some recommended GeoIP Redirect apps here). A lot of translation apps also have this feature built in and they also manage your domain suffixes.
Two translation apps that use the Shopify API, as far as I know, are Langify and LangShop. Perhaps their demos can give you a good idea how they work:
Do you have the Shopify Markets feature activated in your shop? This feature is a one-stop-shop for all your cross-border selling needs and requirements. See more on that here.
Hope that helps!