Let me add some insights and information, @Veselin.
Currently, we're unable to customize the invoice to adopt a custom-calculated field, and setting a Home Currency in AED is unavailable right now.
It could be beneficial if we're able to customize the invoice to adopt with the AED tax and set the company to a foreign currency. Please know that our Development Team is looking for innovative features like what you've shared now.
I'd also suggest visiting our developer's Community site to share your insights about this functionality. Then, click the QuickBooks Online tile and the Ask a question button.
In the meantime, you'll want to create a new company set for AED home currency. You can check this link for more details: QuickBooks Online UAE. Having this account will help calculate the VAT that you can assign to products/services.
For additional info about how multicurrency works and about exchange rates, you can reference this article: About Multicurrency.
I'm always a post away if you have other concerns with QuickBooks. I'll keep my notifications. Stay safe and have a good one!