Hi there s-avramovic1-gma,
Thanks for reaching out about invoices. QuickBooks Online is a great tool able to help create and send invoices for your customers. I can provide some information about invoices and multicurrency.
The Multicurrency feature is available to the Essentials, Plus and Advanced Plan. You can follow the steps to turn on Multicurrency as well add a customer with foreign currency so you can invoice them in this article about multicurrency.
If you have any other questions, feel free to reach out here.