Only stores using Shopify Payments can use this feature that is built into Shopify. If you want your store to display your products in the currency based on your customers location, this can be accomplished by the way of an app. There is a list of currency conversions apps that you can check out in our app store, here.
With that said, I've heard great things about Bucks Currency Converter. Best of all, it's currently free to use. Their app can automatically convert to 160+ currencies based on the customers location. Their app can also automatically convert the pricing of your products based on the customers geolocation.
It's important to note that while a currency app will display the product prices in their native currency to get an understanding of. how much it will cost them. The checkout currency will still be to the one that you have set up in your Shopify store settings.
If there is anything else I can help you with, please let me know.
Here is the link you may refer to that payment providers that is available in Belgium: https://www.shopify.ca/payment-gateways/belgium. Regarding multiple currency solutions, there are options like Stripe you can look up.
Additionally, as you provide multiple currencies to your visitors, you may potentially consider auto display and upon checking out using local currencies according to your visitors locations. It brings local to your customers immediately and boost customer conversion rates. For example, you may consider Geo Targetly. When the currency is changed, it adds a parameter to the URL, like exampleshop.cum?cur=USD or exampleshop.com?cur=AUD. Its Geo Redirect tool can auto direct your visitors to correct URLs based on their IP geolocations. You can easily set up location rules with each targeted markets associated with its URLs within a few steps. No code is required and Shopify platform is supported.
Hope it helps!
Here I suggest one solution that is allow for all the currency.
Let your customers pick a currency as per their nationality from multiple currency options with a flag against each through the currency switcher AppJetty GeoIP Redirect offers and is compatible with the native Shopify multi-currency support. you can see this in following image.